arXiv:1410.6681v1 [astro-ph.IM] 24 Oct 2014 GPS Timing and Control System of the HAWC Detector. A. U. Abeysekara∗a,b , T. N. Ukwattaa , D. Edmundsa , J. T. Linnemanna , A. Imranc , G. J. Kunded , I. G. Wisherc a Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA b Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, USA c Wisconsin IceCube Particle Astrophysics Center (WIPAC) and Department of Physics, University of Wisconsin-Madison, Madison, WI, USA d Physics Division, Los Alamos National Laboratory, Los Alamos, NM, USA Abstract The design and performance of the GPS Timing and Control (GTC) System of the High Altitude Water Cerenkov (HAWC) gamma ray observatory is described. The GTC system provides a GPS synchronized absolute timestamp, with an accuracy better than 1µs, for each recorded event in HAWC. In order to avoid any slack between the recorded data and the timestamp, timestamps are injected to the main data acquisition (DAQ) system after the Front-end Electronic Boards (FEBs). When HAWC is completed, the HAWC main DAQ will use 10 time to digital converters (TDCs). In order to keep all the TDCs in sync, the GTC system provides a synchronized clock signal, coordinated trigger signal, and control signals to all TDCs. Keywords: GPS timestamp, gamma-ray astrophysics, water cherenkov detector, time to digital converter, TeV astronomy Contents 1 Introduction 2 2 HAWC Observatory 3 ∗ Corresponding author: [email protected] Preprint submitted to NIM October 27, 2014 Latest results of NEXT-DEMO, the prototype of the NEXT 100 double beta decay experiment L. Serraa,∗, D. Lorcaa , J. Mart´ın-Alboa , M. Sorela , J.J. G´omez-Cadenasa , on behalf of the NEXT Collaboration de F´ısica Corpuscular (IFIC), CSIC & Universidad de Valencia Abstract NEXT-DEMO is a 1:4.5 scale prototype of the NEXT100 detector, a high-pressure xenon gas TPC that will search for the neutrinoless double beta decay of 136 Xe. X-ray energy depositions produced by the de-excitation of Xenon atoms after the interaction of gamma rays from radioactive sources have been used to characterize the response of the detector obtaining the spatial calibration needed for close-to-optimal energy resolution. Our result, 5.5% FWHM at 30 keV, extrapolates to 0.6% FWHM at the Q value of 136 Xe. Additionally, alpha decays from radon have been used to measure several detection properties and parameters of xenon gas such as electron-ion recombination, electron drift velocity, diffusion and primary scintillation light yield. Alpha spectroscopy is also used to quantify the activity of radon inside the detector, a potential source of background for most double beta decay experiments. Keywords: time projection chamber, x-ray, alpha decay, double beta decay, NEXT 1. The NEXT-DEMO prototype ee- ee- scintillation (S1) ee- electroluminescence (S2) CATHODE TRACKING PLANE (SiPMs) NEXT-100 is a 100-kg high-pressure xenon gas electroluminescent TPC [1]. It will search for the neutrinoless double beta decay of 136 Xe in the Laboratorio Subterr´aneo de Canfranc (LSC). The features that make NEXT a powerful ββ0ν experiment are very good energy resolution, tracking capabilities and scalability to large detector masses. ENERGY PLANE (PMTs) arXiv:1410.6700v1 [physics.ins-det] 24 Oct 2014 a Instituto ANODE Figure 1: The NEXT detector concept. A plane of PMTs lo- cated behind a transparent cathode detects both S1 and S2 signal measuring start of event time and the energy of event. On the other side, a plane of SiPMs detects the forward EL light, providing topological information of the event. ∗ Corresponding author e-mail: [email protected] NEXT-DEMO is a 1-kg prototype built to demonstrate the detector concept to be used in NEXT 100,outlined in Fig. 1. The xenon active volume of the TPC comprises a 30 cm drift region, operated at a drift voltage between 200-1000 V · cm−1 and a 0.5 cm EL region with a reduced electric field of 1-2 kV · cm −1 · bar−1 . The pressure is 10 bar for all the studies presented here. It has been running for 3 years using different radioactive sources. Some measurements made so far include energy resolution, imaging of single and double electron tracks and xenon gas properties (drift velocity, diffusion) [2, 3, 4, 5, 6]. 2. Studies with electromagnetic depositions X-ray depositions have been used to determine the energy response of the TPC, needed to achieve the goal energy resolution [5]. XY energy response has been measured in the active volume of the detector in order to homogenize the response in the energy plane. Drift velocity is obtained by studying the temporal distribution of these events, shown in Fig. 2. Using the primary scintillation we are able to measure the drift time of the electrons coming from the cathode, the full drift length, and obtain the drift velocity. Results are consistent with previous measurement using alpha particle depositions [6]. In addition, these events are used Backgrounds and sensitivity of the NEXT double beta decay experiment M. Nebot-Guinota,∗, P. Ferrarioa , J. Mart´ın-Alboa , J. Mu˜noz Vidala , J.J. G´omez-Cadenasa , on behalf of the NEXT Collaboration de F´ısica Corpuscular (IFIC), CSIC & Universitat de Val`encia Calle Catedr´atico Jos´e Beltr´an, 2, 46980 Paterna, Valencia, Spain arXiv:1410.6699v1 [physics.ins-det] 24 Oct 2014 a Instituto Abstract NEXT (Neutrino Experiment with a Xenon TPC) is a neutrinoless double-beta (ββ0ν) decay experiment that will operate at the Canfranc Underground Laboratory (LSC). It is an electroluminescent high-pressure gaseous xenon Time Projection Chamber (TPC) with separate read-out planes for calorimetry and tracking. Energy resolution and background suppression are the two key features of any neutrinoless double beta decay experiment. NEXT has both good energy resolution (< 1% FWHM) at the Q value of 136 Xe and an extra handle for background identification provided by track reconstruction. With the background model of NEXT, based on the detector simulation and the evaluation of the detector radiopurity, we can determine the sensitivity to a measurement of the ββ2ν mode in NEW and to a ββ0ν search in NEXT100. In this way we can predict the background rate of 5 × 10−4 counts/(keV kg yr), and a sensitivity to the Majorana neutrino mass down to 100 meV after a 5-years run of NEXT100. Keywords: time projection chamber, radioactivity, background, double beta decay, NEXT 1. Neutrinoless double beta decay Neutrinoless double beta decay (ββ0ν) is a postulated nuclear transition in which two neutrons undergo β decay simultaneously without the emission of neutrinos. Evidence of this process would establish that massive neutrinos are Majorana particles, provide a hint of a new physics scale beyond the Standard Model and prove the violation of total lepton number, a key element to explain the observed asymmetry between matter and antimatter in the universe. In addition, the measurement of the ββ0ν-decay rate would provide information on the absolute scale of neutrino masses [1], as shown in Eq.1: 0ν −1 T 1/2 ∝ m2ββ (1) 2. Double beta decay experiments Double beta decay detectors measure the sum of the kinetic energies from the two released electrons, Qββ. Considering the finite energy resolution (∆E) of any detector, other processes occurring in the detector, as the tail of the ββ2ν mode, can fall in the region of energies around Qbb becoming background. As in other rare ∗ Corresponding author e-mail: [email protected] event detectors, backgrounds of cosmogenic origin and natural radioactivity from materials are a problem, and thus underground operation and selection of radiopure materials is essential. In this sense additional experimental features are desired to improve the sensitivity of the detector, such as extra background (B) rejection, better detector efficiency () or larger exposure (M · t) [1]. This relation can be summarized as follows : r M·t T 1/2 ∝ a · (2) ∆E · B 3. NEXT-100 The NEXT-100 detector will search for the neutrinoless double beta decay of 136 Xe at the Laboratorio Subterraneo de Canfranc. It uses a time projection chamber filled with 100 kg of enriched xenon gas at 15 bar pressure, with separated detection functions for calorimetry and tracking [2]. The gaseous xenon provides scintillation and ionization as primary signals. These are used to establish the start-of-event time (t0 ) and for calorimetry/tracking respectively. In order to achieve optimal energy resolution, the ionization signal is amplified in NEXT using the electroluminescence (EL) of xenon [3]. Calorimetry : The energy plane is made of 60 photomultiplier tubes (Hamamatsu R11410-10 PMTs), lo- Preprint typeset in JINST style - HYPER VERSION FERMILAB-PUB-14-402-E arXiv:1410.6496v1 [physics.ins-det] 23 Oct 2014 Scalability, scintillation readout and charge drift in a kilogram scale solid xenon particle detector J. Yoo∗, H. Cease, W. F. Jaskierny, D. Markley, and R. B. Pahlka Fermi National Accelerator Laboratory, Kirk and Pine St., Batavia, IL 60510, USA D. Balakishiyeva and T. Saab Department of Physics, University of Florida, Gainesville, FL 32611, USA M. Filipenko Erlangen Center for Astroparticle Physics (ECAP), Friedrich Alexander University of Erlangen-Nuremberg, Erwin-Rommel-Stra¨sse 1, 91058 Erlangen, Germany A BSTRACT: We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employ a liquid nitrogen cooled cryostat combined with a xenon purification and chiller system to measure the scintillation light output and electron drift speed from both the solid and liquid phases of xenon. Scintillation light output from sealed radioactive sources is measured by a set of high quantum efficiency photomultiplier tubes suitable for cryogenic applications. We observed a reduced amount of photons in solid phase compared to that in liquid phase. We used a conventional time projection chamber system to measure the electron drift time in a kilogram of solid xenon and observed faster electron drift speed in the solid phase xenon compared to that in the liquid phase. K EYWORDS : Solid-noble element detector, scintillators, charge transport. ∗ Corresponding Author: [email protected] Nuclear Physics B Proceedings Supplement Nuclear Physics B Proceedings Supplement 00 (2014) 1–7 SUSY fits with full LHC Run I data Kees Jan de Vries (on behalf of the MasterCode Collaboration)a arXiv:1410.6755v1 [hep-ph] 24 Oct 2014 a High Energy Physics Group, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2AZ, UK Abstract We present the latest results from the MasterCode collaboration on supersymmetric models, in particular on the CMSSM, the NUHM1, the NUHM2 and the pMSSM. We combine the data from LHC Run I with astrophysical observables, flavor and electroweak precision observables. We determine the best fit regions of these models and analyze the discovery potential of squarks and gluinos at LHC Run II and direct detection experiments. Keywords: Supersymmetry, CMSSM, NUHM1, NUHM2, pMSSM 1. Introduction Despite the absence of any convincing signal of supersummetry (SUSY) after Run 1 at the large hadron collider (LHC), SUSY remains well motivated. First of all, the lightest neutralino is a natural DM candidate. Secondly, SUSY provides a solution to the hierarchy problem. Finally, SUSY allows for unification of the gauge coupling at the so-called grand unified theory (GUT) scale of O(1016 GeV). In these proceedings we present a selection of the results from global frequentist fits of constrained models of SUSY - the CMSSM, NUHM1, NUHM2 and pMSSM10 (defined below) - to experimental constraints from Run I LHC data, astrophysical observables, flavor and electroweak observables. The fits allow us to identify the relevant parameters, assess and compare the validity of the models and study the predictions and consequences for future searches and experiments. In particular, we focus on the differences between GUT-scale and phenomenological models highlighting the (g−2)µ constraint. We discuss the discovery potential for gluinos and squarks at LHC Run II as well as prospects for direct detection of dark matter. Note that the results presented in these proceedings date from the ICHEP2014 conference. We have published elsewhere some of the results shown in these proceedings, namely on the CMSSM, NUHM1 and NUHM2 [1, 2]. We would also like to mention that there are several other groups that perform global fits of SUSY using Bayesian as well as frequentist methods. Some recent fits of CMSSM, NUHM1 and NUHM2 may be found in [3–6], whereas results on the pMSSM may be found in [7, 8]. We will soon publish updated results on pMSSM10. 2. Analysis procedure 2.1. Models We consider four constrained versions of the general R-parity-conserving Minimal Supersymmetric extension of the Standard Model (MSSM). Three of these models are derived from GUT model-building considerations, where masses and couplings are assumed to unify at the GUT scale: In the constrained MSSM (CMSSM) all scalars (two Higgs doublets and the sfermions) have a universal soft SUSY-breaking mass m0 , the gauginos a universal mass m1/2 , and the trilinear couplings are all equal to A0 . In the NUHM1 the masses of the Higgs doublets are assumed to be independent but equal, while in the NUHM2 they are allowed to vary independently. In general m20 can take negative values, q and so we denote in this paper m0 ≡ Sign(m20 ) |m20 | < 0. The remaining parameters of these models are the superpotential coupling µ between the Higgs doublets arXiv:1410.6753v1 [physics.pop-ph] 24 Oct 2014 The symmetry and simplicity of the laws of physics and the Higgs boson Juan Maldacena Institute for Advanced Study, Princeton, NJ 08540, USA Abstract We describe the theoretical ideas, developed between the 1950s-1970s, which led to the prediction of the Higgs boson, the particle that was discovered in 2012. The forces of nature are based on symmetry principles. We explain the nature of these symmetries through an economic analogy. We also discuss the Higgs mechanism, which is necessary to avoid some of the naive consequences of these symmetries, and to explain various features of elementary particles. What can radiative decays of the X(3872) teach us about its nature? Feng-Kun Guoa , C. Hanhartb , Yu.S. Kalashnikovac , Ulf-G. Meißnera,b , A.V. Nefedievc,d,e arXiv:1410.6712v1 [hep-ph] 24 Oct 2014 a Helmholtz-Institut f¨ ur Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universit¨ at Bonn, D-53115 Bonn, Germany b Forschungszentrum J¨ ulich, Institute for Advanced Simulation, Institut f¨ ur Kernphysik and J¨ ulich Center for Hadron Physics, D-52425 J¨ ulich, Germany c Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia d National Research Nuclear University MEPhI, 115409, Moscow, Russia e Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Moscow Region, Russia Abstract ¯ ∗ molecule, we discuss the radiative Starting from the hypothesis that the X(3872) is a D D ′ decays of the X(3872) into γJ/ψ and γψ from an effective field theory point of view. We show that radiative decays are not sensitive to the long-range structure of the X(3872). In particular, contrary to earlier claims, we argue that the experimentally determined ratio of the mentioned branching fractions is not in conflict with a wave function of the X(3872) ¯ ∗ hadronic molecular component. that is dominated by the D D Keywords: exotic hadrons, charmonium 1. Introduction The X(3872) was discovered by the Belle Collaboration in 2003 [1]. It has a mass ¯ ∗0 threshold, and thus it has been regarded as one of the most extremely close to the D 0 D promising candidates for a hadronic molecule, which can be either an S-wave bound state [2– ¯ ∗ system [8]. Its quantum numbers were determined by the 7] or a virtual state in the D D LHCb Collaboration to be J P C = 1++ [9] 10 years after the discovery. Other models exist in addition to the hadronic molecule interpretation, which include a radial excitation of the P -wave charmonium χc1 (2P ) [10], a tetraquark [11], a mixture of an ordinary charmonium and a hadronic molecule [12, 13], or a state generated in the coupled-channel dynamical scheme [14, 15]. It was claimed in Ref. [16] that the radiative decays of the X(3872) into the γJ/ψ and γψ ′ (here and in what follows ψ ′ denotes ψ(2S)) are very sensitive to its structure. Especially, using vector meson dominance and a quark model, in Ref. [16] it was predicted that the ratio R≡ B(X(3872) → γψ ′ ) B(X(3872) → γJ/ψ) (1) is about 4 × 10−3 , if the X(3872) is a hadronic molecule with the dominant component ¯ ∗0 plus a small admixture of the ρJ/ψ and ωJ/ψ. Various quark model calculations D0D Preprint submitted to Physics Letters B October 27, 2014 Progress in Double Parton Scattering Studies Sunil Bansal,1 Paolo Bartalini* ,2 Boris Blok,3 Diego Ciangottini,4, 5 Markus Diehl,6 Fiorella M. Fionda,7, 8 Jonathan R. Gaunt,6 Paolo Gunnellini,4, 5 Tristan Du Pree,9 Tomas Kasemets,10, 11 Daniel Ostermeier,12 Sergio Scopetta,4, 5 Andrzej Si´odmok,13 Alexander M. Snigirev,14 Antoni Szczurek,15, 16 Daniele Treleani*,17, 18 and Wouter J. Waalewijn* 10, 19 1 Department of Physics, University of Antwerp, 2020 Antwerp, Belgium Department of Physics, Central China Normal University, 430079 Wuhan, China 3 Department of Physics, Technion - Israel Institute of Technology, Haifa, Israel 4 Dipartimento di Fisica, Universit` a degli Studi di Perugia, 06100 Perugia, Italy 5 INFN, sezione di Perugia, via A. Pascoli, 06100 Perugia, Italy 6 Theory Group, Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany 7 Dipartimento interateneo di Fisica, Universit` a degli Studi di Bari, Via Amendola 173, 70126 Bari, Italy 8 INFN, sezione di Bari, Via E. Orabona n. 4, 70125 Bari, Italy 9 Universit´e Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium 10 Nikhef, Theory Group, Science Park 105, 1098 XG, Amsterdam, The Netherlands 11 Department of Physics and Astronomy, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands 12 Institut f¨ ur Theoretische Physik, Universit¨ at Regensburg, 93040 Regensburg, Germany 13 School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, U.K. 14 Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow, Russia 15 Institute of Nuclear Physics PAN, PL-31-342 Cracow, Poland 16 University of Rzesz´ ow, PL-35-959 Rzesz´ ow, Poland 17 Dipartimento di Fisica dellUniversit di Trieste, Trieste, Italy 18 INFN, Sezione di Trieste, Strada Costiera 11, Miramare-Grignano, I-34151 Trieste, Italy 19 ITFA, University of Amsterdam, Science Park 904, 1018 XE, Amsterdam, The Netherlands (Dated: October 27, 2014) arXiv:1410.6664v1 [hep-ph] 24 Oct 2014 2 An overview of theoretical and experimental progress in double parton scattering (DPS) is presented. The theoretical topics cover factorization in DPS, models for double parton distributions and DPS in charm production and nuclear collisions. On the experimental side, CMS results for dijet and double J/ψ production, in light of DPS, as well as first results for the 4-jet channel are presented. ALICE reports on a study of open charm and J/ψ multiplicity dependence. I. limitations and proper generalization of Eq. (1). This is reflected in the variety of topics discussed within the DPS track at this workshop: PROGRESS IN THE THEORY OF DOUBLE PARTON SCATTERING A. Introduction • Progress in factorization for DPS Theoretical predictions for double parton scattering (DPS) require a factorization theorem for the cross section, in order to separate the two short-distance collisions from the long-range physics of the incoming protons. The partonic cross section of the hard scatterings is perturbatively calculable. The momenta of the quarks and gluons inside the proton are described by non-perturbative (double) parton distribution functions (PDFs), which must be modeled or extracted from data. If the two hard scatterings are independent and the two incoming partons in each proton are completely independent, the DPS cross section simplifies to σDPS σ1 σ2 = , Sσeff (1) with σ1 and σ2 the standard cross sections of the individual scatterings and S a symmetry factor. This leaves a single nonperturbative parameter σeff , which only affects the total DPS rate. For certain applications this approximation is sufficient, but one would also like to know the • Double parton correlations in proton models • DPS in charm cross sections • DPS in nuclear collisions B. Progress in Factorization A factorization analysis of DPS [1–3] reveals a large number of effects that are not included in the “pocket formula” in Eq. (1): • Correlations between the two momentum fractions, the transverse separation of partons and/or flavor • Spin correlations between the partons • Color correlations between the partons • Interferences in fermion number • Interferences in flavor ULB-TH/14-15, LPN14-119, ZU-TH35/14, STUPP-14-220 LHC Tests of Light Neutralino Dark Matter without Light Sfermions Lorenzo Calibbi arXiv:1410.5730v1 [hep-ph] 21 Oct 2014 ? ? 1, Jonas M. Lindert † 2, Toshihiko Ota ‡ 3, Yasutaka Takanishi ∗ 4 Service de Physique Th´eorique, Universit´e Libre de Bruxelles, Bld du Triomphe, CP225, B-1050 Brussels, Belgium † Physik-Institut, Universit¨ at Z¨ urich, Wintherturerstrasse 190, CH-8057 Z¨ urich, Switzerland ‡ Department of Physics, Saitama University, Shimo-Okubo 255, 338-8570 Saitama-Sakura, Japan ∗ Max-Planck-Institut f¨ ur Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany Abstract We address the question how light the lightest MSSM neutralino can be as dark matter candidate in a scenario where all supersymmetric scalar particles are heavy. The hypothesis that the neutralino accounts for the observed dark matter density sets strong requirements on the supersymmetric spectrum, thus providing an handle for collider tests. In particular for a lightest neutralino below 100 GeV the relic density constraint translates into an upper bound on the Higgsino mass parameter µ in case all supersymmetric scalar particles are heavy. One can define a simplified model that highlights only the necessary features of the spectrum and their observable consequences at the LHC. Reinterpreting recent searches at the LHC we derive limits on the mass of the lightest neutralino that, in many cases, prove to be more constraining than dark matter experiments themselves. 1 E-mail: E-mail: 3 E-mail: 4 E-mail: 2 [email protected] [email protected] [email protected] [email protected] EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2014-238 2014/10/27 CMS-SMP-12-028 arXiv:1410.6765v1 [hep-ex] 24 Oct 2014 Constraints on parton distribution functions and extraction of the strong coupling constant from√ the inclusive jet cross section in pp collisions at s = 7 TeV The CMS Collaboration∗ Abstract The inclusive jet cross section for proton-proton collisions at a centre-of-mass energy of 7 TeV was measured by the CMS Collaboration at the LHC with data corresponding to an integrated luminosity of 5.0 fb−1 . The measurement covers a phase space up to 2 TeV in jet transverse momentum and 2.5 in absolute jet rapidity. The statistical precision of these data leads to stringent constraints on the parton distribution functions of the proton. The data provide important input for the gluon density at high fractions of the proton momentum and for the strong coupling constant at large energy scales. Using predictions from perturbative quantum chromodynamics at next-toleading order, complemented with electroweak corrections, the constraining power of these data is investigated and the strong coupling constant at the Z boson mass MZ 0.0060 is determined to be αS ( MZ ) = 0.1185 ± 0.0019 (exp) + −0.0037 (theo), which is in agreement with the world average. Submitted to the European Physical Journal C c 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license ∗ See Appendix C for the list of collaboration members EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2014-243 2014/10/27 CMS-HIG-13-007 arXiv:1410.6679v1 [hep-ex] 24 Oct 2014 Search for a standard model-like Higgs boson in the µ+ µ− and e+ e− decay channels at the LHC The CMS Collaboration∗ Abstract A search is presented for a standard model-like Higgs boson decaying to the µ+ µ− or e+ e− final states based on proton-proton collisions recorded by the CMS experiment at the CERN LHC. The data correspond to integrated luminosities of 5.0 fb−1 at a centre-of-mass energy of 7 TeV and 19.7 fb−1 at 8 TeV for the µ+ µ− search, and of 19.7 fb−1 at 8 TeV for the e+ e− search. To enhance the sensitivity of the search, events are categorized by topologies according to production process and dilepton invariant mass resolution. Upper limits on the production cross section times branching fraction at the 95% confidence level are reported for Higgs boson masses in the range from 120 to 150 GeV. For a Higgs boson with a mass of 125 GeV decaying to µ+ µ− , 2.8 the observed (expected) upper limit on the production rate is found to be 7.4 (6.5+ −1.9 ) times the standard model value. This corresponds to an upper limit on the branching fraction of 0.0016. Similarly, for e+ e− , an upper limit of 0.0019 is placed on the branching fraction, which is ≈3.7 × 105 times the standard model value. These results, together with recent evidence of the 125 GeV boson coupling to τ-leptons with a larger branching fraction consistent with the standard model, show for the first time that the leptonic couplings of the new boson are not flavour-universal. Submitted to Physics Letters B c 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license ∗ See Appendix A for the list of collaboration members arXiv:1410.6615v1 [hep-ex] 24 Oct 2014 Longitudinal target-spin asymmetries for deeply virtual Compton scattering E. Seder,1, 2 A. Biselli,3 S. Pisano,4, 5 S. Niccolai,5, ∗ G.D. Smith,6, 7 K. Joo,1 K. Adhikari,8 M.J. Amaryan,8 M.D. Anderson,6 S. Anefalos Pereira,4 H. Avakian,9 M. Battaglieri,10 I. Bedlinskiy,11 J. Bono,12 S. Boiarinov,9 P. Bosted,9, 13 W. Briscoe,14 J. Brock,9 W.K. Brooks,15 S. B¨ ultmann,8 V.D. Burkert,9 D.S. Carman,9 C. Carlin,9 A. Celentano,10 S. Chandavar,16 G. Charles,5 L. Colaneri,17 P.L. Cole,18 M. Contalbrigo,19 D. Crabb,20 V. Crede,21 A. D’Angelo,17, 22 N. Dashyan,23 R. De Vita,10 E. De Sanctis,4 A. Deur,9 C. Djalali,24 D. Doughty,25, 9 R. Dupre,5, 26 L. El Fassi,8 L. Elouadrhiri,9 P. Eugenio,21 G. Fedotov,24, 27 S. Fegan,10, 6 A. Filippi,28 J.A. Fleming,7 A. Fradi,5 B. Garillon,5 M. Gar¸con,2 N. Gevorgyan,23 Y. Ghandilyan,23 K.L. Giovanetti,29 F.X. Girod,9, 2 J.T. Goetz,16 W. Gohn,1, † R.W. Gothe,24 K.A. Griffioen,13 B. Guegan,5 M. Guidal,5 L. Guo,12 K. Hafidi,26 H. Hakobyan,15, 23 C. Hanretty,20, ‡ N. Harrison,1 M. Hattawy,5 N. Hirlinger Saylor,30, § M. Holtrop,31 S.M. Hughes,7 Y. Ilieva,24 D.G. Ireland,6 B.S. Ishkhanov,27 E.L. Isupov,27 H.S. Jo,5 S. Joosten,32 C.D. Keith,9 D. Keller,20, 16 G. Khachatryan,23 M. Khandaker,18, 33 A. Kim,34, ¶ W. Kim,34 A. Klein,8 F.J. Klein,35 S. Koirala,8 V. Kubarovsky,9 S.E. Kuhn,8 P. Lenisa,19 K. Livingston,6 H.Y. Lu,24 I.J.D. MacGregor,6 N. Markov,1 M. Mayer,8 B. McKinnon,6 D.G. Meekins,9 T. Mineeva,1 M. Mirazita,4 V. Mokeev,9, 27 R. Montgomery,4 C.I. Moody,26 H. Moutarde,2 A Movsisyan,19 C. Munoz Camacho,5 P. Nadel-Turonski,9, 35 I. Niculescu,29 M. Osipenko,10 A.I. Ostrovidov,21 M. Paolone,32 L.L. Pappalardo,19 K. Park,9, 24, ∗∗ S. Park,21 E. Pasyuk,9, 36 P. Peng,20 W. Phelps,12 O. Pogorelko,11 J.W. Price,37 Y. Prok,8 D. Protopopescu,6 A.J.R. Puckett,1 M. Ripani,10 A. Rizzo,17 G. Rosner,6 P. Rossi,4, 9 P. Roy,21 F. Sabati´e,2 C. Salgado,33 D. Schott,14, 12 R.A. Schumacher,38 I. Senderovich,36 A. Simonyan,23 I. Skorodumina,24 D. Sokhan,6, 7 N. Sparveris,32 S. Stepanyan,9 P. Stoler,30 I.I. Strakovsky,14 S. Strauch,24 V. Sytnik,15 M. Taiuti,10, 39 W. Tang,16 Y. Tian,24 M. Ungaro,9, 1 H. Voskanyan,23 E. Voutier,40 N.K. Walford,35 D.P. Watts,7 X. Wei,9 L.B. Weinstein,8 M.H. Wood,41, 24 N. Zachariou,24 L. Zana,7 J. Zhang,9, 8 and I. Zonta17 (The CLAS Collaboration) 1 University of Connecticut, Storrs, Connecticut 06269 CEA, Centre de Saclay, Irfu/Service de Physique Nucl´eaire, 91191 Gif-sur-Yvette, France 3 Fairfield University, Fairfield, Connecticut 06824 4 INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy 5 Institut de Physique Nucl´eaire Orsay, 91406 Orsay, France 6 University of Glasgow, Glasgow G12 8QQ, United Kingdom 7 Edinburgh University, Edinburgh EH9 3JZ, United Kingdom 8 Old Dominion University, Norfolk, Virginia 23529 9 Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 10 INFN, Sezione di Genova, 16146 Genova, Italy 11 Institute of Theoretical and Experimental Physics, Moscow, 117259, Russia 12 Florida International University, Miami, Florida 33199 13 College of William and Mary, Williamsburg, Virginia 23187-8795 14 The George Washington University, Washington, D.C. 20052 15 Universidad T´ecnica Federico Santa Mar´ıa, Casilla 110-V Valpara´ıso, Chile 16 Ohio University, Athens, Ohio 45701 17 INFN, Sezione di Roma Tor Vergata, 00133 Roma, Italy 18 Idaho State University, Pocatello, Idaho 83209 19 INFN, Sezione di Ferrara, 44100 Ferrara, Italy 20 University of Virginia, Charlottesville, Virginia 22901 21 Florida State University, Tallahassee, Florida 32306 22 Universit` a di Roma Tor Vergata, 00133 Roma, Italy 23 Yerevan Physics Institute, 375036 Yerevan, Armenia 24 University of South Carolina, Columbia, South Carolina 29208 25 Christopher Newport University, Newport News, Virginia 23606 26 Argonne National Laboratory, Argonne, Illinois 60439 27 Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119234 Moscow, Russia 28 INFN, Sezione di Torino, Torino, Italy 29 James Madison University, Harrisonburg, Virginia 22807 30 Rensselaer Polytechnic Institute, Troy, New York 12180-3590 31 University of New Hampshire, Durham, New Hampshire 03824-3568 32 Temple University, Philadelphia, Pennsylvania 19122 33 Norfolk State University, Norfolk, Virginia 23504 34 Kyungpook National University, Daegu 702-701, Republic of Korea 35 Catholic University of America, Washington, D.C. 20064 36 Arizona State University, Tempe, Arizona 85287-1504 2 2 37 California State University, Dominguez Hills, Carson, California 90747 38 Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 39 Universit` a di Genova, 16146 Genova, Italy 40 LPSC, Universit´e Grenoble-Alps, CNRS/IN2P3, Grenoble, France 41 Canisius College, Buffalo, New York 14208 (Dated: October 27, 2014) A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e0 p0 γ events, which arise from the interference of the deeply virtual Compton scattering and the BetheHeitler processes, were extracted over the widest kinematics in Q2 , xB , t and φ, for 166 fourdimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even GPDs. PACS numbers: 12.38.-t, 13.40.-f, 13.60.-r, 25.30.-c, 25.30.Rw, 25.30.Dh, 25.30.Fj Nearly 60 years after Hofstadter’s direct measurement of the finite size of the proton [1], the way the bulk properties of the nucleon, such as its mass and spin, are connected to the dynamics of its constituents is still a subject of intense research. Quantum Chromo-Dynamics (QCD), the fundamental theory of the strong interaction, is still unsolved for quarks confined in the nucleon. Therefore, phenomenological functions need to be used to connect experimental observables with the inner dynamics of the constituents of the nucleons, the partons. The Generalized Parton Distributions (GPDs), introduced two decades ago, have emerged as a universal tool to describe hadrons, and nucleons in particular, in terms of their elementary constituents, quarks and gluons [2–7]. The GPDs combine and generalize the features of the form factors measured in elastic scattering and of the parton distribution functions obtained via deep inelastic scattering (DIS). In a reference frame in which the nucleon moves at the speed of light, the GPDs correlate the longitudinal momentum and the transverse position of partons in a given helicity state. They can also give access to the contribution to the nucleon spin from the orbital angular momentum of the quarks, via Ji’s sum rule [4]. At leading order in the QCD coupling constant αs and at leading twist (i.e. neglecting quark-gluon interactions or higher-order quark loops), considering only quark GPDs and quark-helicity conserving quantities, there are four e E, e which can different GPDs for the nucleon: H, E, H, be measured in exclusive electroproduction reactions at ∗ † ‡ § ¶ ∗∗ corresponding author: [email protected] Current address:University of Kentucky, Lexington, Kentucky 40506 Current address:Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 Current address:University of Massachusetts, Amherst, Massachusetts 01003 Current address:University of Connecticut, Storrs, Connecticut 06269 Current address:Old Dominion University, Norfolk, Virginia 23529 FIG. 1. (Color online) The “handbag” diagram for the DVCS process on the proton ep → e0 p0 γ. t = (p − p0 )2 is the squared four-momentum transfer between the initial and final protons. xB ξ is proportional to the Bjorken variable xB (ξ ' 2−x , where B 2 Q xB = 2M , M is the proton mass and ν = Ee − Ee0 ). x is not ν accessible experimentally in the DVCS process. high electron-momentum transfer. Deeply virtual Compton scattering (DVCS) (ep → e0 p0 γ, Fig. 1) is the simplest process to access the GPDs of the proton. At high γ ∗ virtuality Q2 = −(e − e0 )2 , and at leading twist, which is valid at small squared momentum transfer to the proton −t relative to Q2 , this process corresponds to the absorption of a virtual photon by a quark carrying a fraction (x + ξ) of the longitudinal momentum of the proton with respect to its direction. The struck quark emits a real photon, as a result of which its final longitudinal momentum fraction is (x − ξ). The amplitude for DVCS can be factorized [4] into a hardscattering part (calculable in perturbative QCD) and a non-perturbative part, representing the soft structure of the nucleon, parametrized by the GPDs that depend on the three kinematic variables x, ξ, and t. The definitions of the kinematic variables are in the caption of Fig. 1. The Fourier transform, at ξ = 0, of the t dependence of a GPD provides the spatial distribution in the transverse plane for partons having a longitudinal momentum fraction x. DVCS shares the same final state with the BetheHeitler (BH) process, where a real photon is emitted by arXiv:1410.6538v1 [hep-ex] 24 Oct 2014 Study of e+ e− → ωχcJ at center-of-mass energies from 4.21 to 4.42 GeV M. Ablikim1 , M. N. Achasov8,a , X. C. Ai1 , O. Albayrak4 , M. Albrecht3 , D. J. Ambrose42 , A. Amoroso46A,46C , F. F. An1 , Q. An43 , J. Z. Bai1 , R. Baldini Ferroli19A , Y. Ban30 , D. W. Bennett18 , J. V. Bennett4 , M. Bertani19A , D. Bettoni20A , J. M. Bian41 , F. Bianchi46A,46C , E. Boger22,g , O. Bondarenko24 , I. Boyko22 , R. A. Briere4 , H. Cai48 , X. Cai1 , O. Cakir38A , A. Calcaterra19A , G. F. Cao1 , S. A. Cetin38B , J. F. Chang1 , G. Chelkov22,b , G. Chen1 , H. S. Chen1 , H. Y. Chen2 , J. C. Chen1 , M. L. Chen1 , S. J. Chen28 , X. Chen1 , X. R. Chen25 , Y. B. Chen1 , H. P. Cheng16 , X. K. Chu30 , Y. P. Chu1 , G. Cibinetto20A , D. Cronin-Hennessy41 , H. L. Dai1 , J. P. Dai1 , D. Dedovich22 , Z. Y. Deng1 , A. Denig21 , I. Denysenko22 , M. Destefanis46A,46C , F. De Mori46A,46C , Y. Ding26 , C. Dong29 , J. Dong1 , L. Y. Dong1 , M. Y. Dong1 , S. X. Du50 , P. F. Duan1 , J. Z. Fan37 , J. Fang1 , S. S. Fang1 , X. Fang43 , Y. Fang1 , L. Fava46B,46C , F. Feldbauer21 , G. Felici19A , C. Q. Feng43 , E. Fioravanti20A , C. D. Fu1 , Q. Gao1 , Y. Gao37 , I. Garzia20A , K. Goetzen9 , W. X. Gong1 , W. Gradl21 , M. Greco46A,46C , M. H. Gu1 , Y. T. Gu11 , Y. H. Guan1 , A. Q. Guo1 , L. B. Guo27 , T. Guo27 , Y. Guo1 , Y. P. Guo21 , Z. Haddadi24 , A. Hafner21 , S. Han48 , Y. L. Han1 , F. A. Harris40 , K. L. He1 , Z. Y. He29 , T. Held3 , Y. K. Heng1 , Z. L. Hou1 , C. Hu27 , H. M. Hu1 , J. F. Hu46A , T. Hu1 , Y. Hu1 , G. M. Huang5 , G. S. Huang43 , H. P. Huang48 , J. S. Huang14 , X. T. Huang32 , Y. Huang28 , T. Hussain45 , Q. Ji1 , Q. P. Ji29 , X. B. Ji1 , X. L. Ji1 , L. L. Jiang1 , L. W. Jiang48 , X. S. Jiang1 , J. B. Jiao32 , Z. Jiao16 , D. P. Jin1 , S. Jin1 , T. Johansson47 , A. Julin41 , N. Kalantar-Nayestanaki24 , X. L. Kang1 , X. S. Kang29 , M. Kavatsyuk24 , B. C. Ke4 , R. Kliemt13 , B. Kloss21 , O. B. Kolcu38B,c , B. Kopf3 , M. Kornicer40 , W. Kuehn23 , A. Kupsc47 , W. Lai1 , J. S. Lange23 , M. Lara18 , P. Larin13 , Cheng Li43 , C. H. Li1 , D. M. Li50 , F. Li1 , G. Li1 , H. B. Li1 , J. C. Li1 , Jin Li31 , K. Li12 , K. Li32 , P. R. Li39 , T. Li32 , W. D. Li1 , W. G. Li1 , X. L. Li32 , X. M. Li11 , X. N. Li1 , X. Q. Li29 , Z. B. Li36 , H. Liang43 , Y. F. Liang34 , Y. T. Liang23 , G. R. Liao10 , D. X. Lin13 , B. J. Liu1 , C. L. Liu4 , C. X. Liu1 , F. H. Liu33 , Fang Liu1 , Feng Liu5 , H. B. Liu11 , H. H. Liu1 , H. H. Liu15 , H. M. Liu1 , J. Liu1 , J. P. Liu48 , J. Y. Liu1 , K. Liu37 , K. Y. Liu26 , L. D. Liu30 , Q. Liu39 , S. B. Liu43 , X. Liu25 , X. X. Liu39 , Y. B. Liu29 , Z. A. Liu1 , Zhiqiang Liu1 , Zhiqing Liu21 , H. Loehner24 , X. C. Lou1,d , H. J. Lu16 , J. G. Lu1 , R. Q. Lu17 , Y. Lu1 , Y. P. Lu1 , C. L. Luo27 , M. X. Luo49 , T. Luo40 , X. L. Luo1 , M. Lv1 , X. R. Lyu39 , F. C. Ma26 , H. L. Ma1 , L. L. Ma32 , Q. M. Ma1 , S. Ma1 , T. Ma1 , X. N. Ma29 , X. Y. Ma1 , F. E. Maas13 , M. Maggiora46A,46C , Q. A. Malik45 , Y. J. Mao30 , Z. P. Mao1 , S. Marcello46A,46C , J. G. Messchendorp24 , J. Min1 , T. J. Min1 , R. E. Mitchell18 , X. H. Mo1 , Y. J. Mo5 , H. Moeini24 , C. Morales Morales13 , K. Moriya18 , N. Yu. Muchnoi8,a , H. Muramatsu41 , Y. Nefedov22 , F. Nerling13 , I. B. Nikolaev8,a , Z. Ning1 , S. Nisar7 , S. L. Niu1 , X. Y. Niu1 , S. L. Olsen31 , Q. Ouyang1 , S. Pacetti19B , P. Patteri19A , M. Pelizaeus3 , H. P. Peng43 , K. Peters9 , J. L. Ping27 , R. G. Ping1 , R. Poling41 , Y. N. Pu17 , M. Qi28 , S. Qian1 , C. F. Qiao39 , L. Q. Qin32 , N. Qin48 , X. S. Qin1 , Y. Qin30 , Z. H. Qin1 , J. F. Qiu1 , K. H. Rashid45 , C. F. Redmer21 , H. L. Ren17 , M. Ripka21 , G. Rong1 , X. D. Ruan11 , V. Santoro20A , A. Sarantsev22,e , M. Savri´e20B , K. Schoenning47 , S. Schumann21 , W. Shan30 , M. Shao43 , C. P. Shen2 , P. X. Shen29 , X. Y. Shen1 , H. Y. Sheng1 , M. R. Shepherd18 , W. M. Song1 , X. Y. Song1 , S. Sosio46A,46C , S. Spataro46A,46C , B. Spruck23 , G. X. Sun1 , J. F. Sun14 , S. S. Sun1 , Y. J. Sun43 , Y. Z. Sun1 , Z. J. Sun1 , Z. T. Sun18 , C. J. Tang34 , X. Tang1 , I. Tapan38C , E. H. Thorndike42 , M. Tiemens24 , D. Toth41 , M. Ullrich23 , I. Uman38B , G. S. Varner40 , B. Wang29 , B. L. Wang39 , D. Wang30 , D. Y. Wang30 , K. Wang1 , L. L. Wang1 , L. S. Wang1 , M. Wang32 , P. Wang1 , P. L. Wang1 , Q. J. Wang1 , S. G. Wang30 , W. Wang1 , X. F. Wang37 , Y. D. Wang19A , Y. F. Wang1 , Y. Q. Wang21 , Z. Wang1 , Z. G. Wang1 , Z. H. Wang43 , Z. Y. Wang1 , D. H. Wei10 , J. B. Wei30 , P. Weidenkaff21 , S. P. Wen1 , U. Wiedner3 , M. Wolke47 , L. H. Wu1 , Z. Wu1 , L. G. Xia37 , Y. Xia17 , D. Xiao1 , Z. J. Xiao27 , Y. G. Xie1 , Q. L. Xiu1 , G. F. Xu1 , L. Xu1 , Q. J. Xu12 , Q. N. Xu39 , X. P. Xu35 , L. Yan43 , W. B. Yan43 , W. C. Yan43 , Y. H. Yan17 , H. X. Yang1 , L. Yang48 , Y. Yang5 , Y. X. Yang10 , H. Ye1 , M. Ye1 , M. H. Ye6 , J. H. Yin1 , B. X. Yu1 , C. X. Yu29 , H. W. Yu30 , J. S. Yu25 , C. Z. Yuan1 , W. L. Yuan28 , Y. Yuan1 , A. Yuncu38B,f , A. A. Zafar45 , A. Zallo19A , Y. Zeng17 , B. X. Zhang1 , B. Y. Zhang1 , C. Zhang28 , C. C. Zhang1 , D. H. Zhang1 , H. H. Zhang36 , H. Y. Zhang1 , J. J. Zhang1 , J. L. Zhang1 , J. Q. Zhang1 , J. W. Zhang1 , J. Y. Zhang1 , J. Z. Zhang1 , K. Zhang1 , L. Zhang1 , S. H. Zhang1 , X. J. Zhang1 , X. Y. Zhang32 , Y. Zhang1 , Y. H. Zhang1 , Z. H. Zhang5 , Z. P. Zhang43 , Z. Y. Zhang48 , G. Zhao1 , J. W. Zhao1 , J. Y. Zhao1 , J. 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Zou1 (BESIII Collaboration) 1 7 Institute of High Energy Physics, Beijing 100049, People’s Republic of China 2 Beihang University, Beijing 100191, People’s Republic of China 3 Bochum Ruhr-University, D-44780 Bochum, Germany 4 Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA 5 Central China Normal University, Wuhan 430079, People’s Republic of China 6 China Center of Advanced Science and Technology, Beijing 100190, People’s Republic of China COMSATS Institute of Information Technology, Lahore, Defence Road, Off Raiwind Road, 54000 Lahore, Pakistan 8 G.I. Budker Institute of Nuclear Physics SB RAS (BINP), Novosibirsk 630090, Russia 9 GSI Helmholtzcentre for Heavy Ion Research GmbH, D-64291 Darmstadt, Germany 10 Guangxi Normal University, Guilin 541004, People’s Republic of China 11 GuangXi University, Nanning 530004, People’s Republic of China 12 Hangzhou Normal University, Hangzhou 310036, People’s Republic of China 13 Helmholtz Institute Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, Germany 14 Henan Normal University, Xinxiang 453007, People’s Republic of China Typeset by REVTEX 2 15 Henan University of Science and Technology, Luoyang 471003, People’s Republic of China 16 Huangshan College, Huangshan 245000, People’s Republic of China 17 Hunan University, Changsha 410082, People’s Republic of China 18 Indiana University, Bloomington, Indiana 47405, USA 19 (A)INFN Laboratori Nazionali di Frascati, I-00044, Frascati, Italy; (B)INFN and University of Perugia, I-06100, Perugia, Italy 20 (A)INFN Sezione di Ferrara, I-44122, Ferrara, Italy; (B)University of Ferrara, I-44122, Ferrara, Italy 21 Johannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, Germany 22 Joint Institute for Nuclear Research, 141980 Dubna, Moscow region, Russia 23 Justus Liebig University Giessen, II. Physikalisches Institut, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany 24 KVI-CART, University of Groningen, NL-9747 AA Groningen, The Netherlands 25 Lanzhou University, Lanzhou 730000, People’s Republic of China 26 Liaoning University, Shenyang 110036, People’s Republic of China 27 Nanjing Normal University, Nanjing 210023, People’s Republic of China 28 Nanjing University, Nanjing 210093, People’s Republic of China 29 Nankai University, Tianjin 300071, People’s Republic of China 30 Peking University, Beijing 100871, People’s Republic of China 31 Seoul National University, Seoul, 151-747 Korea 32 Shandong University, Jinan 250100, People’s Republic of China 33 Shanxi University, Taiyuan 030006, People’s Republic of China 34 Sichuan University, Chengdu 610064, People’s Republic of China 35 Soochow University, Suzhou 215006, People’s Republic of China 36 Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China 37 Tsinghua University, Beijing 100084, People’s Republic of China 38 (A)Ankara University, Dogol Caddesi, 06100 Tandogan, Ankara, Turkey; (B)Dogus University, 34722 Istanbul, Turkey; (C)Uludag University, 16059 Bursa, Turkey 39 University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China 40 University of Hawaii, Honolulu, Hawaii 96822, USA 41 University of Minnesota, Minneapolis, Minnesota 55455, USA 42 University of Rochester, Rochester, New York 14627, USA 43 University of Science and Technology of China, Hefei 230026, People’s Republic of China 44 University of South China, Hengyang 421001, People’s Republic of China 45 University of the Punjab, Lahore-54590, Pakistan 46 (A)University of Turin, I-10125, Turin, Italy; (B)University of Eastern Piedmont, I-15121, Alessandria, Italy; (C)INFN, I-10125, Turin, Italy 47 Uppsala University, Box 516, SE-75120 Uppsala, Sweden 48 Wuhan University, Wuhan 430072, People’s Republic of China 49 Zhejiang University, Hangzhou 310027, People’s Republic of China 50 Zhengzhou University, Zhengzhou 450001, People’s Republic of China b a Also at the Novosibirsk State University, Novosibirsk, 630090, Russia Also at the Moscow Institute of Physics and Technology, Moscow 141700, Russia and at the Functional Electronics Laboratory, Tomsk State University, Tomsk, 634050, Russia c Currently at Istanbul Arel University, Kucukcekmece, Istanbul, Turkey d Also at University of Texas at Dallas, Richardson, Texas 75083, USA e Also at the PNPI, Gatchina 188300, Russia f Also at Bogazici University, 34342 Istanbul, Turkey g Also at the Moscow Institute of Physics and Technology, Moscow 141700, Russia Based on data samples collected with the BESIII detector at the BEPCII collider at 9 center-ofmass energies from 4.21 to 4.42 GeV, we search for the production of e+ e− → ωχcJ (J = √ 0, 1, 2). The process e+ e− → ωχc0 is observed for the first time, and the Born cross sections at s = 4.23 and 4.26 GeV are measured to be (55.4 ± 6.0 ± 5.9) and (23.7 ± 5.3 ± 3.5) pb, respectively, where the first uncertainties are statistical and the second are systematic. The ωχc0 signals at the other 7 energies and e+ e− → ωχc1 and ωχc2 signals are not significant, and the upper limits on the cross sections are determined. By examining the ωχc0 cross section as a function of center-of-mass energy, we find that it is inconsistent with the line shape of the Y (4260) observed in e+ e− → π + π − J/ψ. PACS numbers: 14.40.Rt, 13.66.Bc, 14.40.Pq, 13.25.Jx The charmonium-like state Y (4260) was first ob- served in its decay to π + π − J/ψ [1], and has small Is the X(3915) the χc0 (2P )? Stephen Lars Olsen1 arXiv:1410.6534v1 [hep-ex] 24 Oct 2014 1 Center for Underground Physics, Institute for Basic Science, Daejeon 305-811, Korea (Dated: October 27, 2014) The Particle Data Group has assigned the X(3915) meson, an ωJ/ψ mass peak seen in B → KωJ/ψ decays and γγ → ωJ/ψ two-photon fusion reactions, as the χc0 (2P ), the 23 P0 charmonium state. Here it is shown that if the X(3915) is the χc0 (2P ), the measured strength of the γγ → X(3915) signal implies an upper limit on the branching fraction B(χc0 (2P ) → ωJ/ψ) < 7.8% that conflicts with a > 14.3% lower limit derived for the same quantity from the B → KX(3915) ¯ 0 in B + → K + D0 D ¯ 0 decays is decay rate. Also, the absence any signal for X(3915) → D0 D ¯ 0 < 1.2 × B(X(3915) → ωJ/ψ). This contradicts used to establish the limit B(X(3915) → D0 D ¯ 0 would be a dominant process, while decays to ωJ/ψ, expectations that χc0 (2P ) decays to D0 D which are Okubo-Zweig-Iizuka suppressed, would be relatively rare. These, plus reasons given earlier by Guo and Meissner, raise serious doubts about the X(3915) = χc0 (2P ) assignment. PACS numbers: 14.40.Pq, 13.25.Gv INTRODUCTION values of the mass and width are [7]: M (X(3915)) = 3918.4 ± 1.9 MeV A number of meson candidates, dubbed the XY Z mesons, that contain charmed-quark anticharmed-quark (c¯ c) pairs but do not match expectations for any of the unassigned levels of the c¯ c charmonium spectrum have been observed in recent experiments. Some have non-zero electric charge [1] and cannot be accommodated in the spectrum of charmonium mesons, which are all electrically neutral. Others are neutral and have quantum numbers that are accessible by c¯ c systems, but have properties that fail to match the tightly constrained expectations of any of the unassigned charmonium states [2]. To date, there is no compelling theoretical explanation for these XY Z mesons. Experimental observations of additional states and more refined measurements of properties of the existing states may eventually reveal patterns that give clues to their underlying structure. An important part of this program is a careful distinction of new states that are conventional charmonium mesons from those that are not. The X(3915) was observed by Belle as a near-threshold peak in the ωJ/ψ invariant mass distribution in exclusive B → KωJ/ψ decays [3]; it was subsequently confirmed by BaBar [4]. An ωJ/ψ mass peak with similar mass and width was reported by Belle in the two-photon fusion process γγ → ωJ/ψ in 2010 [5]. BaBar reported confirmation of the γγ → X(3915) → ωJ/ψ observation [6] and, from a study of the angular correlations among the final-state particles, established the J P C quantum numbers to be 0++ . The similar masses and widths of the peaks seen in B decay and in two-photon fusion processes suggest that these are two different production mechanisms for the same state. The Particle Data Group’s (PDG) average Γ(X(3915)) = 20.0 ± 5.0 MeV. (1) The weighted average of the Belle [3] and BaBar [4] product branching fraction measurements for X(3915) production in B decay is B(B + → K + X(3915)) × B(X(3915) → ωJ/ψ) = 3.2 ± 0.9 × 10−5 , (2) while the average of measured production rates in two-photon fusion (using J P C = 0++ ) gives [7] Γγγ X(3915) × B(X(3915) → ωJ/ψ) = 54 ± 9eV, (3) where Γγγ X(3915) is the partial width for X(3915) → γγ. The presence of a J/ψ among its decay products indicate that the X(3915) contains a c¯ c quark pair. The only unassigned 0++ charmonium level in the vicinity of the X(3915) mass is the χc0 (2P ), the first radial exitation of the χc0 charmonium state. (In the following, the χc0 (2P ) referred to as the χ′c0 .) Because of this, the PDG identifies the X(3915) as the χ′c0 . This assignment was disputed by Guo and Meissner [8], primarily because: • the partial width for X(3915) → ωJ/ψ is too large for a decay process that is Okubo-Zweig-Iizuka (OZI) suppressed for a charmonium state; ¯ decays, • the lack of evidence for X(3915) → DD which are expected to be dominant χ′c0 decay modes; • the small χc2 (2P )-χc0 (2P ) mass splitting. If the X(3915) is not conventional charmonium but, instead, another XY Z meson, it would be the lightest Anisotropic hydrodynamics for conformal Gubser flow Mohammad Nopoush Kent State University, Kent OH 44242 USA Radoslaw Ryblewski The H. Niewodnicza´ nski Institute of Nuclear Physics, arXiv:1410.6790v1 [nucl-th] 24 Oct 2014 Polish Academy of Sciences, PL-31342 Krak´ow, Poland Michael Strickland Kent State University, Kent OH 44242 USA Abstract We derive the equations of motion for a system undergoing boost-invariant longitudinal and azimuthally-symmetric transverse “Gubser” flow using leading-order anisotropic hydrodynamics. This is accomplished by assuming that the one-particle distribution function is ellipsoidallysymmetric in the momenta conjugate to the de Sitter coordinates used to parametrize the Gubser flow. We then demonstrate that the SO(3)q symmetry in de Sitter space further constrains the anisotropy tensor to be of spheroidal form. The resulting system of two coupled ordinary differential equations for the de Sitter space momentum scale and anisotropy parameter are solved numerically and compared to a recently obtained exact solution of the relaxation-time-approximation Boltzmann equation subject to the same flow. We show that anisotropic hydrodynamics describes the spatio-temporal evolution of the system better than all currently known dissipative hydrodynamics approaches. In addition, we prove that anisotropic hydrodynamics gives the exact solution of the relaxation-time approximation Boltzmann equation in the ideal, η/s → 0, and free-streaming, η/s → ∞, limits. 1 arXiv:1410.6689v1 [astro-ph.HE] 24 Oct 2014 Prepared for submission to JCAP Antiproton signatures from astrophysical and dark matter sources at the galactic center J. A. R. Cembranosa,b,c V. Gammaldia A. L. Marotoa a Departamento de Física Teórica I, Universidad Complutense de Madrid, E-28040 Madrid, Spain; b Facultad c Dual de Ciencias, CUICBAS, Universidad de Colima, 28040 Colima, Mexico; C-P Institute of High Energy Physics, 28040 Colima, Mexico. E-mail: [email protected], [email protected], [email protected] Abstract. The center of our Galaxy is a complex region characterized by extreme phenomena. The presence of the supermassive Sagittarius A* black hole, a high Dark Matter (DM) density and an even higher baryonic density are able to produce very energetic processes. Indeed, high energetic gamma rays have been observed by different telescopes, although its origin is not clear. In this work, we constrain the possible antiproton flux component associated to this signal. The expected secondary astrophysical antiproton background already saturates the observed data. It implies that any other important astrophysical source leads to an inconsistent excess, since the theoretical uncertainties corresponding to the mentioned background are small. The constraints depend on the diffusion model and the spectral features of the source. In particular, we consider antiproton spectra described by a power-law, a monochromatic signal and a Standard Model particle-antiparticle channel production. A New Look at Those Old Black Holes: Existence of Universal Horizons Kai Lin a,b , O. Goldoni c,d , M.F. da Silva d , and Anzhong Wang a,d∗ a b arXiv:1410.6678v1 [gr-qc] 23 Oct 2014 d Institute for Advanced Physics & Mathematics, Zhejiang University of Technology, Hangzhou 310032, China Instituto de F´ısica, Universidade de S˜ ao Paulo, CP 66318, 05315-970, S˜ ao Paulo, Brazil c Departamento de F´ısica Te´ orica, Universidade do Estado do Rio de Janeiro, Rua S˜ ao Francisco Xavier 524, Maracan˜ a, CEP 20550013, Rio de Janeiro, RJ, Brazil GCAP-CASPER, Physics Department, Baylor University, Waco, TX 76798-7316, USA (Dated: October 27, 2014) In this paper, we study the existence of universal horizons in static spacetimes, and find that the khronon field can be solved explicitly when its velocity becomes infinitely large, in which the universal horizons coincide with the sound horizon of the khronon. Choosing the timelike coordinate aligned with the khronon, the static metric takes a simple form, from which it can be seen clearly that the metric now is free of singularity at the Killing horizons, but becomes singular at the universal horizons. Applying such developed formulas to three well-known black hole solutions, the Schwarzschild, Schwarzschild anti-de Sitter, and Reissner-Nordstr¨ om, we find that in all these solutions universal horizons exist and are always inside the Killing horizons. The peeling-off behavior of the khronon depends on the coordinates adopted. In particular, in the Schwarzschild coordinates the khronon is peeling off at both Killing and universal horizons, while in the Eddington-Finkelstein and Painleve-Gullstrand coordinates, the peeling-off behavior is found only when across the universal horizons. We also calculate the surface gravity at each of the universal horizons, and find that the surface gravity at the universal horizon is always greeter than that at the Killing horizon. PACS numbers: 04.60.-m; 98.80.Cq; 98.80.-k; 98.80.Bp I. INTRODUCTION hypersurface-orthogonal and timelike vector field uµ , u[ν Dα uβ] = 0. The studies of black holes have been one of the main objects both theoretically and observationally over the last half of century [1, 2], and so far there are many solid observational evidences for their existence in our universe. Theoretically, such investigations have been playing a crucial role in the understanding of the nature of gravity in general, and quantum gravity in particular. They started with the discovery of the laws of black hole mechanics [3] and Hawking radiation [4], and led to the profound recognition of the thermodynamic interpretation of the four laws [5] and the reconstruction of general relativity (GR) as the thermodynamic limit of a more fundamental theory of gravity [6]. More recently, they are essential in understanding the AdS/CFT correspondence [7, 8] and firewalls [9]. Lately, such studies have gained further momenta in the framework of gravitational theories with broken Lorentz invariance (LI) [10–13]. In particular, Blas and Sibiryakov showed that an absolute horizon exists with respect to any signal with any large velocity, including the one with infinitely large one (instantaneous propagation) [10]. Such a horizon is dubbed as the universal horizon, which is always located inside a Killing horizon. A critical point is the existence of a globally well-defined ∗ The corresponding author E-mail: Anzhong [email protected] (1.1) Then, it implies that there exists a scalar field φ [14], so that φ,µ uµ = √ , X (1.2) where φ,µ ≡ ∂φ/∂xµ , X ≡ −g αβ ∂α φ∂β φ. Clearly, uµ is invariant under the gauge transformations, φ˜ = F(φ), (1.3) where F(φ) is a monotonically increasing and otherwise arbitrary function of φ. Such a scalar field was often referred to as the khronon [15], and is equivalent to the Einstein-aether (Æ-) theory [16], when the aether uµ is hypersurface-orthogonal, as showed explicitly in [17] (See also [18]). Note that in the studies of the existence of the universal horizons carried out so far [10–13], the khronon field is always part of the underlined theory of gravity. To generalize such definitions to any theories that violate LI, recently the khronon φ was promoted to a probe field, and assumed that it plays the same role as a Killing vector field in a given space-time, so its existence does not affect the background, but defines the properties of it [19]. By this way, such a field is no longer part of the gravitational field and it may or may not exist in a given space-time. Applied such a generalized definition of the universal horizons to static charged solutions of the healthy extensions [15] of the Hoˇrava-Lifshitz (HL) Magnetic field instability in a neutron star driven by electroweak electron-nucleon interaction versus chiral magnetic effect arXiv:1410.6676v1 [astro-ph.HE] 24 Oct 2014 a Maxim Dvornikova,b and Victor B. Semikozb Institute of Physics, University of S˜ ao Paulo, CP 66318, CEP 05315-970 S˜ ao Paulo, SP, Brazil; b Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN), 142190 Troitsk, Moscow, Russia (Dated: October 27, 2014) We show that the Standard Model electroweak interaction of ultrarelativistic electrons with nucleons (eN interaction) in a neutron star (NS) permeated by a seed large-scale helical magnetic field provides its growth up to & 1015 G during a time comparable with the ages of young magnetars ∼ 104 yr. The magnetic field instability originates from the parity violation in the eN interaction entering the generalized Dirac equation for right and left massless electrons in an external uniform magnetic field. The averaged electric current given by the solution of the modified Dirac equation contains an extra current for right and left electrons (positrons). Such current includes both a changing chiral imbalance of electrons and the eN potential given by a constant neutron density in NS. Then we derive the system of the kinetic equations for the chiral imbalance and the magnetic helicity which accounts for the eN interaction. By solving this system, we show that a sizable chiral imbalance arising in a neutron protostar due to the Urca-process e− L + p → N + νeL diminishes very rapidly because of a huge chirality flip rate. Thus the eN term prevails the chiral effect providing a huge growth of the magnetic helicity and the helical magnetic field. PACS numbers: 97.60.Jd, 11.15.Yc, 25.30.Bf Some neutron stars (NSs), called magnetars, having magnetic fields B ∼ 1015 − 1016 G, can be considered as strongest magnets in our universe [1]. Despite the existence of various models for the generation of such strong fields, based, e.g., on the turbulent dynamo [2], the origin of magnetic fields in magnetars is still an open problem. Recently, in Ref. [3] the authors tried to apply the chiral magnetic effect [4, 5], adapted successfully for the QED plasma [6], to tackle the problem of magnetic fields in magnetars. The approach of Ref. [3] implies the chiral kinetic theory, where Vlasov equation is modified when adding the Berry curvature term to the Lorentz force [7]. The fate of such a chiral plasma instability is based on the Adler anomaly in QED with the nonconservation of the pseudovector current for massless fermions ¯ µ γ5 ψ in external electromagnetic fields. Since this ψγ current is the difference of right jµR and left jµL currents, the assumption of a seed imbalance between their densities given by the difference of chemical potentials, (nR − nL ) ∼ µ5 = (µR − µL )/2 6= 0, where nR,L are the densities of right and left fermions (electrons) and µR,L are their chemical potentials, could lead to the magnetic field instability we study here adding electroweak interactions in the Standard Model (SM). The same effect (while without weak interactions) was used in Ref. [8] to study the self-consistent evolution of the magnetic helicity in the hot plasma of the early Universe driven by the change of the lepton asymmetry ∼ µ5 . In Ref. [8] it was showed that such an asymmetry diminishes, µ5 → 0, due to the growth of the chirality flip rate in the cooling universe through electron-electron (ee) col2 1 e2 e lisions, Γf ∼ α2em m ≈ 137 is the , where αem = 4π 3T fine structure constant, me is the electron mass, and T is the plasma temperature. This negative result encouraged the appearance of Ref. [9], where another mechanism for the generation of magnetic fields was proposed. It is based on the parity violation in electroweak plasma resulting in the nonzero Chern-Simons (CS) term Π2 that enters the antisymmetric part of the photon polarization operator in plasma of massless particles. Here we adopt the notation for the CS term from Ref. [9]. In Ref. [10], a similar CS term (νl) Π2 , based on the neutrino interactions with charged leptons, was calculated. Basing on this calculation, the magnetic field instability driven by neutrino asymmetries was revealed. This instability is implemented in different media such as the hot plasma of the early universe and a supernova (SN) with a seed magnetic field. The amplification of a seed magnetic field during the SN burst driven by a non-zero electron neutrino asym(νe) metry ∆nνe 6= 0 which enters the CS term Π2 was suggested in Ref. [10] to explain the generation of strongest magnetic fields in magnetars. Note that after the SN burst a cooling NS as the corresponding SN remnant emits equally neutrinos and antineutrinos. Thus, the neutrino asymmetry vanishes. The inclusion of the electroweak ee-interaction with a stable fraction of degenerate electrons ne ≈ const instead of the νe interaction with vanishing neutrino asymmetry ∆nνe → 0 has no sense since the corresponding parity violating CS term (ee) Π2 tends to zero in the static limit ω → 0 for an elec- Spontaneous supersymmetry breaking in the 2d N = 1 Wess-Zumino model Kyle Steinhauer and Urs Wenger∗ Albert Einstein Center for Fundamental Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland. (Dated: October 27, 2014) We study the phase diagram of the two-dimensional N = 1 Wess-Zumino model on the lattice using Wilson fermions and the fermion loop formulation. We give a complete nonperturbative determination of the ground state structure in the continuum and infinite volume limit. We also present a determination of the particle spectrum in the supersymmetric phase, in the supersymmetry broken phase and across the supersymmetry breaking phase transition. In the supersymmetry broken phase we observe the emergence of the Goldstino particle. arXiv:1410.6665v1 [hep-lat] 24 Oct 2014 PACS numbers: 11.30.Pb,11.30.Qc,12.60.Jv,05.50.+q INTRODUCTION Understanding the spontaneous breakdown of supersymmetry is a generic nonperturbative problem which is relevant not only for particle physics but in fact for many physical systems beyond quantum field theories. The N = 1 Wess-Zumino model [1, 2] in two dimensions is one of the simplest supersymmetric quantum field theories which allows for spontaneous supersymmetry breaking since it enjoys the necessary but not sufficient condition of a vanishing Witten index [3]. The model has been analysed employing various approaches such as Monte Carlo methods [4, 5], Hamiltonian techniques [6–8], or exact renormalisation group methods [9]. Wilson derivatives for fermions and bosons, guaranteeing a supersymmetric continuum limit [10], were used in [11] and a numerical analysis of the phase diagram using the SLAC derivative has been conducted in [12]. All approaches use various regulators which are more or less difficult to control. In this letter we report on our results for the two-dimensional N = 1 Wess-Zumino model regularized on a Euclidean spacetime lattice. The discretization using Wilson derivatives for the fermions and bosons [10] together with the fermion loop formulation and a novel algorithm [13] allows to systematically remove all effects from the IR and UV regulators by explicitly taking the necessary limits in a completely controlled way. One reason why this has not been achieved so far with other methods is the fact that all supersymmetric systems with spontaneously broken supersymmetry suffer from a fermion sign problem related to the vanishing of the Witten index [14]. However, that sign problem can be circumvented in our approach by using the exact reformulation of the lattice model in terms of fermion loops [14]. In this formulation the partition function is obtained as a sum over closed fermion loop configurations and separates naturally into its bosonic and fermionic parts for which the sign is perfectly under control. Efficient simulations with an open fermion string (or fermionic worm) algorithm [13] are then possible even in the phase with spontaneously broken supersymmetry where the massless Goldstino mode is present. The two-dimensional N = 1 Wess-Zumino model [1, 2] contains a real two component Majorana spinor ψ and a real bosonic field φ and is described in Euclidean spacetime by the on-shell continuum action ) ( Z 2 0 1 1 [P (φ)] (∂µ φ)2 + ψDψ + (1) S = d2 x 2 2 2 where D = ∂/ + P 00 (φ) is the Majorana Dirac operator. Here, P (φ) denotes a generic superpotential and P 0 and P 00 its first and second derivative with respect to φ, respectively. The action is invariant under a supersymmetry transformation δ which transforms φ, ψ and ψ as δφ = ψ, / − P 0 ), δψ = (∂φ δψ = 0, (2) where is a constant Majorana spinor. In the following we will concentrate on the specific superpotential P (φ) = 1 3 m2 gφ − φ. 3 4g (3) With this potential, the action is also invariant under a discrete Z2 /chiral symmetry transformation φ → −φ, ψ → σ3 ψ, ψ → −ψσ3 (4) which in the following we denote by Zχ2 symmetry. The potential yields a vanishing Witten index W = 0 and hence allows for spontaneous supersymmetry breaking [3]. This can for example be derived from the transformation properties of the Pfaffian Pf(D) under the Z2 symmetry φ → −φ [15]. FERMION LOOP FORMULATION When the model is regularized on a discrete spacetime lattice both the Zχ2 and the supersymmetry are broken explicitly, but the discretization can be chosen such that the restoration of the symmetries is guaranteed in the continuum limit [10]. This can be achieved because the model is superrenormalisable and only one counterterm is necessary to renormalize the bare mass m, while the coupling g is not renormalized and can hence be used to define the continuum limit ag → 0 where a is the lattice RESCEU-44/14 Prospects of determination of reheating temperature after inflation by DECIGO arXiv:1410.6618v1 [astro-ph.CO] 24 Oct 2014 Sachiko Kuroyanagi1, Kazunori Nakayama2, and Jun’ichi Yokoyama3,4 1 Department of Physics, Tokyo University of Science, Kagrazaka, Japan 2 Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 3 Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 4 Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), WPI, TODIAS, The University of Tokyo, Kashiwa, Japan (Dated: October 27, 2014) If the tensor-to-scalar ratio r of cosmological perturbations takes a large value r ∼ 0.1, which may be inferred by recent BICEP2 result, we can hope to determine thermal history, in particular, the reheating temperature, TR , after inflation by space-based laser interferometers. It is shown that upgraded and upshifted versions of DECIGO may be able to determine TR if it lies in the range 6 × 106 < TR < 5 × 107 GeV and 3 × 107 < TR < 2 × 108 GeV, respectively. Although these ranges include predictions of some currently plausible inflation models, since each specification can probe TR of at most a decade range, we should determine the specifications of DECIGO with full account of constraints on inflation models to be obtained by near-future observations of temperature anisotropy and B-model polarization of the cosmic microwave background radiation. After more than three decades from its original proposal [1, 2], the inflationary cosmology is now confronting and passing a number of observational tests. Among its generic predictions, the spatial flatness and generation of almost scale-invariant spectrum of curvature perturbations [3] were first confirmed by precise measurements of the cosmic microwave background radiation (CMB) by WMAP [4, 5] and are now being updated by Planck [6, 7]. The Gaussian nature of these fluctuations has also been further confirmed recently by Planck [8]. In March 2014, the BICEP2 collaboration [9] reported detection of the B-mode polarization of CMB over a fairly wide range of angular multipoles from ℓ ≃ 40 to 350. The higher multipole range can be explained by gravitational lensing while the smaller multipoles are interpreted as owing to the long-wave gravitational waves of primordial origin, most likely from the tensor perturbations generated quantum mechanically during inflationary expansion stage in the early Universe [10]. If what they measured had not been contaminated by foregrounds, it would correspond to the amplitude of the tensor-to-scalar ratio as r = 0.20+0.07 −0.05 [9]. Note that r is related with the energy scale of inflation as V = (3.2 × 1016 GeV)4 r. This value, on the other hand, is larger than that expected by the constraints imposed by WMAP [5] and Planck [7] in terms of temperature anisotropy and E-mode polarization, because they reported 95% upper bounds on r as r < 0.13 and 0.11, respectively, and that the likelihood contours in (ns , r) plane preferred the tensor-to-scalar ratio significantly smaller than 0.1. As a result, models predicting tiny values of r such as r ∼ 10−3 had been investigated extensively including the curvature square inflation [2] and the original Higgs inflation model [11], which occupy the central region of the likelihood contours. These models would be ruled out if large tensor perturbation would be observationally established 1 . After the original announcement of BICEP2, several analyses of the effects of dust contamination have been done, and it has been pointed out that they may be so large that the observed B-mode polarization may be entirely due to the dust foreground [15] and we only have an upper bound on r. In any event, the BICEP2 observation has reminded us the lesson that the truth may not lie in the center of the likelihood contour and we should remain open-minded until the final result is established. Hence here we consider the case with r close to its observational upper bound r ∼ 0.1. The most plausible feature of a relatively large value of r is that direct observation of tensor perturbations becomes more feasible by future space-based laser interferometers such as DECIGO [16], which also allow us to extract useful information on the thermal history after inflation [17]. For example, information on reheating is imprinted in the gravitational wave spectrum in the frequencies corresponding to the energy scale of reheating. Thus, the targeting frequency of the experiment is a key for determining reheating temperature and would be better to be adjusted once we obtain a hint about reheating from either cosmology or 1 Even in such a case the Higgs field in the Standard Model could be an inflaton, because newer Higgs inflation models such as Higgs G-inflation [12] or running kinetic inflation [13] could work well to accommodate large enough r as summarized in [14]. Absolute measurement of thermal noise in a resonant short-range force experiment Absolute measurement of thermal noise in a resonant shortrange force experiment H Yan1, E A Housworth2, H O Meyer1, G Visser3, E Weisman1, and J C Long1,4 1 2 3 Department of Physics, Indiana University, Bloomington, Indiana 47405, USA Department of Mathematics, Indiana University, Bloomington, Indiana 47405, USA Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408, USA (Submitted 12 May 2014; revised 5 August 2014) Planar, double-torsional oscillators are especially suitable for short-range macroscopic force search experiments, since they can be operated at the limit of instrumental thermal noise. As a study of this limit, we report a measurement of the noise kinetic energy of a polycrystalline tungsten oscillator in thermal equilibrium at room temperature. The fluctuations of the oscillator in a high-Q torsional mode with a resonance frequency near 1 kHz are detected with capacitive transducers coupled to a sensitive differential amplifier. The electronic processing is calibrated by means of a known electrostatic force and input from a finite-element model. The measured average kinetic energy, Eexp = (2.0 ± 0.3)·10−21 J, is in agreement with the expected value of 1 2 k BT . PACS numbers: 46.80.+j, 05.40.-a, 04.80.Cc, 07.07.Df, 07.10.Fq 1 Introduction The equipartition theorem predicts that any physical system in thermal equilibrium is associated with energy. In particular, this holds for mechanical systems used in precision force measurements, where the random thermal motion of the detector represents one of the dominant noise sources and may limit the sensitivity that can be achieved [1]. In the experiment reported here, we investigate thermal noise by carrying out a measurement of the random kinetic energy Eexp of a torsional thin-plate detector. In contrast to a previous study of thermal noise in a single-crystal silicon oscillator of similar shape [2], we take a somewhat different approach in which a calibration procedure and a finite-element model are used to produce an absolute measurement of Eexp which can be compared directly to the prediction of the equipartition theorem. 4 Author to whom correspondence should be addressed: [email protected] 1 Lepton-Flavored Scalar Dark Matter with Minimal Flavor Violation arXiv:1410.6803v1 [hep-ph] 24 Oct 2014 Chao-Jung Lee and Jusak Tandean Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei 106, Taiwan Abstract We explore scalar dark matter (DM) that is part of a lepton flavor triplet satisfying symmetry requirements under the hypothesis of minimal flavor violation. The theory contains in addition three right-handed neutrinos that participate in the seesaw mechanism for neutrino mass generation. The stability of the DM is tied to the choice of lepton flavor quantum numbers for the triplet, and its interactions with standard model (SM) particles have minimal flavor violation built-in. The DM couples to SM particles via Higgsportal renormalizable interactions as well as to leptons through dimension-six operators. We consider restrictions on the new scalars from the Higgs boson measurements, observed relic density, DM direct detection experiments, and searches for flavor-violating lepton decays. The viable parameter space can be tested further with future data. Also, we investigate the possibility of the scalar couplings accounting for the tentative hint of Higgs flavor-violating decay h → µτ recently detected in the CMS experiment. They are allowed by constraints from other Higgs data to produce a rate of this decay roughly compatible with the CMS finding. 1 LTH 1025 arXiv:1410.6715v1 [hep-ph] 24 Oct 2014 Momentum subtraction and the R-ratio J.A. Gracey, Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX, United Kingdom. Abstract. We determine the R-ratio for massless quarks in several renormalization schemes to various loop orders. These are the momentum subtraction schemes of Celmaster and Gonsalves as well as the minimal momentum subtraction scheme. The dependence of the R-ratio on the schemes is analysed. 1 QCD Phenomenology arXiv:1410.6686v1 [hep-ph] 24 Oct 2014 Roger José Hernández-Pinto Departamento de Física, FCEyN, Universidad de Buenos Aires, (1428) Pabellón 1 Ciudad Universitaria, Capital Federal, Argentina and Instituto de Física Corpuscular, Universitat de València - Consejo Superior de Investigaciones Científicas, Parc Científic, E-46980 Paterna, Valencia, Spain Abstract. Quantum Chromodynamics is the most successful theory in particle physics. The understanding of all different signals at hadron colliders have been achieved due to the correct interpretation of the theory. In this paper we review some basic features of the theory of strong interactions and how it could be used in order to provide phenomenological distributions for the Large Hadron Collider. The main results presented in here can be found in Ref [1]. Keywords: <Quantum Chromodynamics, Perturbative calculations, Standard-model Higgs bosons> PACS: <12.38.-t, 12.38.Bx, 14.80.Bn> INTRODUCTION The Large Hadron Collider (LHC) is the biggest machine ever built by humanity. Its main purpose, the discovery of the last remaining particle of the Standard Model (SM) was achieved in 2012. Theorists and experimentalists from all around the globe made an enormous effort in order to succeed on this task. Experiments are achieving a very high precision in all measurements, and they are now also pushing theorists to provide phenomenological SM predictions at the same level of accuracy. Besides that, the new era of the LHC is coming, and the disentanglement of the properties of the Higgs particle or the discovery of new physics, require theoretical Monte Carlo simulations, of signal and background, at the highest possible precision. The SM of particle physics is based on a gauge theory of SU(3)c × SU(2)L × U(1)Y and it has been by far the most precise theory of nature. In particular, the sector of the theory which governs the physics of the LHC is the one related with the SU(3)c. The LHC collides protons at center of mass energies of the order of TeVs. Protons are made of quarks and gluons, elementary particles of the SM. The description of these partons is well understood in the framework of Quantum Chromodynamics (QCD). Unfortunately, QCD cannot be solved completely, and usually in order to make theoretical predictions for hadron colliders, one takes the perturbative version of QCD (pQCD). In the perturbative regime, the coupling associated to SU(3)c is considered small and the series expansion is allowed. However, at the LHC, this assumption is only valid just in the moment when the collision occurs and when particles are flowing into detectors this statement could not be longer true. In order to compute observables, it is important to know how to include the perturbative part and the non perturbative one in the calculation. In fact, one way to describe the production of a hadron H at the LHC is a mixing arXiv:1410.6684v1 [hep-ph] 24 Oct 2014 EPJ Web of Conferences will be set by the publisher DOI: will be set by the publisher c Owned by the authors, published by EDP Sciences, 2014 Decay Constants of Beauty Mesons from QCD Sum Rules Wolfgang Lucha1 , a , Dmitri Melikhov2,3, b , and Silvano Simula4, c 1 Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna, Austria 2 Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria 3 D. V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, 119991, Moscow, Russia 4 INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146, Roma, Italy Abstract. Our recently completed analysis of the decay constants of both pseudoscalar and vector beauty mesons reveals that in the bottom-quark sector two specific features of the sum-rule predictions show up: (i) For the input value of the bottom-quark mass in the MS scheme mb (mb ) ≈ 4.18 GeV, the sum-rule result fB ≈ 210–220 MeV for the B meson decay constant is substantially larger than the recent lattice-QCD finding fB ≈ 190 MeV. Requiring QCD sum rules to reproduce the lattice-QCD value of fB yields a significantly larger b-quark mass: mb (mb ) = 4.247 GeV. (ii) Whereas QCD sum-rule predictions for the charmed-meson decay constants fD , fDs , fD∗ and fD∗s are practically independent of the choice of renormalization scale, in the beauty sector the results for the decay constants— and especially for the ratio fB∗ / fB —prove to be very sensitive to the specific scale setting. 1 Correlator, operator product expansion, and heavy-quark mass schemes The starting point of our QCD sum-rule evaluation of the decay constants [1] of beauty mesons is the time-ordered product of two meson interpolating currents, viz., j5 (x) = (mb +m) q(x) ¯ i γ5 b(x) for the B meson and jµ (x) = q(x) ¯ γµ b(x) for the B∗ meson. The correlator of pseudoscalar currents is defined by Z 2 Π(p ) ≡ i d4 x ei p x 0 T j5 (x) j†5 (0) 0 . The Borel transform of this correlation function depends on some Borel parameter τ and takes the form Π(τ) = fB2 MB4 exp −MB2 τ + Z∞ (MB∗ +MP )2 ds e −s τ ρhadr (s) = Z∞ ds e−s τ ρpert (s, µ) + Πpower (τ, µ) . (mb +m)2 The B-meson decay constant fB is defined by h0| j5 (0)|Bi = fB MB2 . In order to remove all excited-state contributions, we adopt the standard assumption of quark–hadron duality: the contributions of excited a e-mail: [email protected] b e-mail: [email protected] c e-mail: [email protected] arXiv:1410.6682v1 [hep-ph] 24 Oct 2014 SQUID-based Resonant Detection of Axion Dark Matter Vladimir A. Popov Institute of Physics, Kazan Federal University, Kremlyovskaya st. 18, Kazan 420008, Russia Abstract A new method for searching for Dark Matter axions is proposed. It is shown that a two-contact SQUID can detect oscillating magnetic perturbations induced by the axions in a strong inhomogeneous magnetic field. A resonant signal is a steplike response in the SQUID current-voltage characteristic at a voltage corresponding to the axion mass with a height depending on the axion energy density near the Earth. The proposed experimental technique appears to be sensitive to the axions with masses ma . 10−4 eV, which is well-motivated by current researches both in cosmology and in particle physics. To understand the nature of the Dark Matter (DM) is among major challenges in the present-day cosmology. A number of particles is considered as DM candidates (WIMPs, sterile neutrinos, ets.) and low mass axions are highly attractive ones. The experimental discovery of the axions would give new insights into cosmological and astrophysical researches as well as into particle physics since the axions play a central role in the solution to the strong CP -problem. This provides that experimental searching for the axions with mass in the range of 10−6 − 10−3 eV is of paramount importance. The experimental techniques [1, 2, 3, 4] for DM axions detection are based on axion-phonon conversation processes. Their theoretical description 1 Nuclear Physics B Proceedings Supplement Nuclear Physics B Proceedings Supplement 00 (2014) 1–5 New method for precise determination of top quark mass at LHC Sayaka Kawabata arXiv:1410.6654v1 [hep-ph] 24 Oct 2014 Department of Physics, Tohoku University, Sendai 980-8578, Japan Abstract A new method to measure the mass of the top quark at the LHC is presented [1]. This method uses lepton energy distribution and ideally does not depend on the velocity distribution of the top quark. We perform a simulation analysis of the top quark mass reconstruction using this method at the leading order, taking account of experimental circumstances. We estimate the sensitivity of the mass determination. The results show that this method is viable in realistic experimental conditions and has a possibility to achieve a good accuracy in determining a theoretically well-defined top quark mass by including higher-order corrections. Keywords: top quark, top quark mass, measurement, LHC, QCD 1. Introduction The mass of the top quark is an important input parameter to various physics. In the electroweak precision tests, the top quark mass gives a large contribution to radiative corrections, and accordingly, its precise value is desired in order to scrutinize possible deviations from the Standard Model (SM) [2, 3]. Furthermore, the stability of the SM vacuum up to the Planck scale depends crucially on the value of the top quark mass [4, 5]. Now that the Higgs boson has been discovered [6, 7] and the SM is getting more established, a demand for precise measurements of the top quark mass is increasing. The top quark mass has been measured at the LHC and Tevatron, and their recent combined result yields [8] mt = 173.34 ± 0.27(stat) ± 0.71(syst) GeV . (1) It achieves 0.4% precision, and more accurate results are expected to be obtained in future analyses [9]. This mass, however, is not identical to the pole mass nor well-defined in perturbative QCD. Since the above measurements utilize Monte Carlo (MC) simulations and reconstruct the mass from final-state momenta including jet momenta, the measured mass depends on the hadronization models in the MCs, which we cannot treat within perturbative QCD [10]. Thus, the definition of the measured mass in perturbative theory is ambiguous, and even its relation to the pole or MS mass is not known [11]. Some alternative methods have been proposed and developed to complement the above measurements with different systematic uncertainties or extract a theoretically well-defined top quark mass [12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22]. However, so far, no method has achieved to obtain a theoretically well-defined mass with high precision. In this paper, we present a new method to measure the top quark mass at the LHC. This method has characteristics of using lepton distributions and basically being independent of the kinematics of the production process of top quarks. Consequently, it does not suffer from the ambiguity of hadronization models. Using this method, we can determine the pole mass and MS mass of the top quark. In Sec. 2, a basis of our method, named the “weight function method”, is presented. We perform a simulation analysis of the top quark mass reconstruction using it and the results are shown in Sec. 3. Section 4 is devoted to conclusions. More details of the analysis and discussions in this paper are given in Ref. [1]. ICCUB-14-062 arXiv:1410.6624v1 [hep-ph] 24 Oct 2014 Unification of Coupling Constants, Dimension six Operators and the Spectral Action Agostino Devastato1,2 , Fedele Lizzi1,2,3 , Carlos Valc´arcel Flores4 and Dmitri Vassilevich4 1 Dipartimento di Fisica, Universit`a di Napoli Federico II 2 INFN, Sezione di Napoli Monte S. Angelo, Via Cintia, 80126 Napoli, Italy 3 Departament de Estructura i Constituents de la Mat`eria, Institut de Ci`encies del Cosmos, Universitat de Barcelona, Barcelona, Catalonia, Spain 4 CMCC-Universidade Federal do ABC, Santo Andr`e, S.P., Brazil [email protected], [email protected], [email protected], [email protected] Abstract We investigate whether inclusion of dimension six terms in the Standard Model lagrangean may cause the unification of the coupling constants at a scale comprised between 1014 and 1017 GeV. Particular choice of the dimension 6 couplings is motivated by the spectral action. Given the theoretical and phenomenological constraints, as well as recent data on the Higgs mass, we find that the unification is indeed possible, with a lower unification scale slightly favoured. Nuclear Physics B Proceedings Supplement Nuclear Physics B Proceedings Supplement 00 (2014) 1–6 On the smallness of the cosmological constant C. D. Froggatta , R. Nevzorovb,c , H. B. Nielsend , A. W. Thomasb a School of Physics and Astronomy, University of Glasgow, Glasgow, UK Centre of Excellence for Particle Physics at the Tera–scale, School of Chemistry and Physics, University of Adelaide, Adelaide SA 5005, Australia c Institute for Theoretical and Experimental Physics, Moscow, 117218, Russia d The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark arXiv:1410.6620v1 [hep-ph] 24 Oct 2014 b ARC Abstract In N = 1 supergravity the scalar potential of the hidden sector may have degenerate supersymmetric (SUSY) and non-supersymmetric Minkowski vacua. In this case local SUSY in the second supersymmetric Minkowski phase can be broken dynamically. Assuming that such a second phase and the phase associated with the physical vacuum are exactly degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced if in the second vacuum local SUSY breaking is induced by gaugino condensation at a scale which is just slightly lower than ΛQCD in the physical vacuum. The presence of a third degenerate vacuum, in which local SUSY and electroweak (EW) symmetry are broken near the Planck scale, may lead to small values of the quartic Higgs self–coupling and the corresponding beta function at the Planck scale in the phase in which we live. Keywords: Supergravity, Cosmological constant, Higgs boson PACS: 04.65.+e, 98.80.Es, 14.80.Bn 1. Introduction It is commonly expected that the exploration of TeV scale physics at the LHC may lead to the discovery of new physics phenomena beyond the Standard Model (SM) that can shed light on the stabilisation of the EW scale. Indeed, if the SM is embedded in a more fundamental theory characterized by a much larger energy scale (e.g. the Planck scale MPl ≈ 1019 GeV) than the EW scale, then due to the quadratically divergent radiative corrections, the Higgs boson tends to acquire a mass of the order of the larger energy scale; excessive finetuning is then required to keep the Higgs mass around the observed value ∼ 125 GeV. Despite the compelling arguments for physics beyond the SM, no signal or indication of its presence has been detected at the LHC so far. Besides there are some reasons to believe that the SM is extremely fine-tuned. Indeed, astrophysical and cosmological observations indicate that there is a dark energy spread all over the Universe which constitutes 70% − 73% of its energy density. A fit to the recent data shows that its value 4 is ρΛ ∼ 10−123 MPl ∼ 10−55 MZ4 [1, 2]. At the same time much larger contributions should come from elec4 troweak symmetry breaking (∼ 10−67 MPl ) and QCD −79 4 condensates (∼ 10 MPl ). The contribution of zero– modes is expected to push the vacuum energy density 4 even higher up to ∼ MPl , i.e. ρΛ ' = X ωb X ωf − 2 2 bosons f ermions Ω "X Z 0 b q |~k|2 + m2b − (1) # 3 Xq d ~k 2 2 ~ |k| + m f ∼ −Ω4 , 3 2(2π) f where the mb and m f are the masses of bosons and fermions while Ω ∼ MPl . Because of the cancellation needed between the contributions of different condensates to ρΛ , the smallness of the cosmological constant should be regarded as a fine–tuning problem. The effect of uu diquark suppression in proton splitting in Monte Carlo event generators V. Uzhinsky1,2 , A. Galoyan3 Monte Carlo event generators assume that protons split into (uu)-diquarks and d-quarks with a probability of 1/3 in strong interactions. It is shown in this paper that using a value of 1/6 for the probability allows one to describe at a semi-quantitative level the NA49 Collaboration data for p + p → p + X reactions at 158 GeV/c. The Fritiof (FTF) model of Geant4 was used to simulate the reactions. The reduced weight of the (uu)-diquarks in protons is expected in the instanton model. Most of the Monte Carlo event generators of multi-particle production assume that nucleons split into diquarks and quarks in strong interactions. In particular, protons split into (ud)-diquarks and uquarks with a probability of 2/3, and into (uu)-diquarks and d-quarks with a probability of 1/3. At the same time, there are various physical signatures that the probabilities can be different [1]. For example, it was assumed in the papers [2], as in many other papers, that the (ud)–u configuration completely dominates in the proton wave function. This was motivated be the instanton model [3] of the QCD vacuum. According to that model, quark-quark interactions are flavor-dependent: they are non-zero only if quarks have different flavors. Thus, (uu)-diquarks must be suppressed in protons [4]. The true weight of the (uu)–d configuration can be estimated using the NA49 Collaboration data [5]. The NA49 Collaboration presented high precision data on particle production in pp interactions at 158 GeV/c including xF , pT and rapidity distributions of various particles (p, n, π ± , K ± , p¯). As shown in [6, 7], Monte Carlo event generators based on the Fritiof model [8, 9] cannot satisfactorily describe the data. The most dramatic situation takes place with a description of the proton spectra. A typical prediction for the xF -spectrum is shown in Figure 1 and is presented by the solid thin line. 1,0 F 0,8 dn/dx arXiv:1410.6612v1 [hep-ph] 24 Oct 2014 PACS: 24.10.Lx, 13.85.-t,13.85.Ni, 14.20.-c 0,6 0,4 0,2 pp->p+X, 158 GeV/c 0,0 0,0 0,2 0,4 0,6 0,8 1,0 x F Figure 1: xF distributions of protons in pp interactions at 158 GeV/c. Closed points are the NA49 experimental data [5]. Lines are results of FTF model simulations: standard proton splitting (solid black), optimal diquark fragmentation function (dashed red), string inversion (dotted blue), diquark suppression (1/6 instead of 1/3) including the optimal fragmentation function and the string inversion (solid thick). 1 CERN, Geneva, Switzerland of Information Technologies, JINR, Dubna, Russia 3 Veksler and Baldin Laboratory of High Energy Physics, JINR, Dubna, Russia 2 Laboratory 1 arXiv:1410.6585v1 [hep-ph] 24 Oct 2014 October 21th, 2014 REFRACTIVE PROPERTIES OF GRAPHENE IN A MEDIUM-STRONG EXTERNAL MAGNETIC FIELD O. Coquand 1 2 , B. Machet 3 4 5 6 Abstract: 1-loop quantum corrections are shown to induce large effects on the refractive index n inside a graphene strip in the presence of a constant and uniform external magnetic field B orthogonal to it. To this purpose, we use the tools of Quantum Field Theory to calculate the photon propagator at 1-loop inside graphene in position space, which leads to an effective vacuum polarization in a brane-like theory of photons interacting with massless electrons at locations confined inside the thin strip (its longitudinal spread is considered to be infinite). The effects factorize into quantum ones, controlled by the value of B and that of the electromagnetic coupling α, and a transmittance function U in which the geometry of the sample and the resulting confinement of the γ e+ e− vertices play major roles. They only concern the so-called “transverse-magnetic” polarization of photons, which suggests (anisotropic) electronic spin resonance of the graphene-born virtual electrons. We consider photons inside the visible spectrum and magnetic fields in the range 1-20 Tesla. At B = 0, quantum effects depend very weakly on α and n is essentially controlled by U ; we recover, then, an opacity for visible light of the same order of magnitude παvac as measured experimentally. 1 Ecole Normale Sup´erieure, 61 avenue du Pr´esident Wilson, F-94230 Cachan 2 [email protected] 3 Sorbonne Universit´e, UPMC Univ Paris 06, UMR 7589, LPTHE, F-75005, Paris, France UMR 7589, LPTHE, F-75005, Paris, France. 5 Postal address: LPTHE tour 13-14, 4e` me e ´ tage, UPMC Univ Paris 06, BP 126, 4 place Jussieu, F-75252 Paris Cedex 05 (France) 6 [email protected] 4 CNRS, 1 arXiv:1410.6583v1 [hep-ph] 24 Oct 2014 Charm contribution to bulk viscosity M. Laine and Kiyoumars A. Sohrabi Institute for Theoretical Physics, Albert Einstein Center, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland Abstract In the range of temperatures reached in future heavy ion collision experiments, hadronic pair annihilations and creations of charm quarks may take place within the lifetime of the plasma. As a result, charm quarks may increase the bulk viscosity affecting the early stages of hydrodynamic expansion. Assuming thermalization, we estimate the charm contribution to bulk viscosity within the same effective kinetic theory framework in which the light parton contribution has been computed previously. The time scale at which this physics becomes relevant is related to the width of the transport peak associated with the trace anomaly correlator, and is found to be < ∼ 20 fm/c for T > ∼ 600 MeV. October 2014 High-energy e+ e− photoproduction in the field of a heavy atom accompanied by bremsstrahlung P.A. Krachkov,1, 2, ∗ R.N. Lee,1, † and A. I. Milstein1, ‡ 1 Budker Institute of Nuclear Physics, 630090 Novosibirsk, Russia arXiv:1410.6566v1 [hep-ph] 24 Oct 2014 2 Novosibirsk State University, 630090 Novosibirsk, Russia (Dated: October 27, 2014) Abstract Helicity amplitudes and differential cross section of high-energy e+ e− photoproduction accompanied by bremsstrahlung in the electric field of a heavy atom are derived. The results are exact in the nuclear charge number and obtained in the leading quasiclassical approximation. They correspond to the leading high-energy small-angle asymptotics of the amplitude. It is shown that, in general, the Coulomb corrections essentially modify the differential cross section as compared to the Born result. When the initial photon is circularly polarized the Coulomb corrections lead to the asymmetry in the distribution over the azimuth angles ϕi of produced particles with respect to the replacement ϕi → −ϕi . PACS numbers: 32.80.-t, 12.20.Ds Keywords: e+ e− photoproduction, bremsstrahlung, Coulomb corrections ∗ † ‡ Electronic address: peter˙[email protected] Electronic address: [email protected] Electronic address: [email protected] 1 i Concerning the Nature of the Cosmic Ray Power Law Exponents A. Widom and J. Swain Physics Department, Northeastern University, Boston MA USA Y.N. Srivastava arXiv:1410.6498v1 [hep-ph] 15 Oct 2014 Physics Department, University of Perugia, Perugia IT We have recently shown that the cosmic ray energy distributions as detected on earthbound, low flying balloon or high flying satellite detectors can be computed by employing the heats of evaporation of high energy particles from astrophysical sources. In this manner, the experimentally well known power law exponents of the cosmic ray energy distribution have been theoretically computed as 2.701178 for the case of ideal Bose statistics, 3.000000 for the case of ideal Boltzmann statistics and 3.151374 for the case of ideal Fermi statistics. By “ideal” we mean virtually zero mass (i.e. ultra-relativistic) and noninteracting. These results are in excellent agreement with the experimental indices of 2.7 with a shift to 3.1 at the high energy ∼ PeV “knee” in the energy distribution. Our purpose here is to discuss the nature of cosmic ray power law exponents obtained by employing conventional thermal quantum field theoretical models such as quantum chromodynamics to the cosmic ray sources in a thermodynamic scheme wherein gamma and zeta function regulation is employed. The key reason for the surprising accuracy of the ideal boson and ideal fermion cases resides in the asymptotic freedom or equivalently the Feynman “parton” structure of the ultra-high energy tails of spectral functions. PACS numbers: 13.85.Tp, 13.85.Dz, 13.85.Lg I. INTRODUCTION As in our preliminary work[1], we seek to understand the nature of the power law exponents {α} which are employed to describe the energy distributions observed in the cosmic rays continually bombarding our planet and coming from astrophysical sources[2–4]. From the quantum field theory viewpoint we regard the cosmic rays as standard model hadrons evaporating from sources and moving away from such sources as a gaseous blowing wind. Such a solar wind exists issuing from the center of our own planetary system. These evaporating winds no doubt also blow away from other astrophysical objects such as neutron stars. The starting point for defining cosmic ray power law exponents was purely experimental. It is known[5] that the energy distribution law of cosmic ray nuclei in the energy range 5 GeV < E < 100 TeV via the differential flux per unit time per unit area per steradian per unit energy obeys α d4 N 1 GeV 1.8 nucleons (1) ≈ dtdAdΩdE sec cm2 sr GeV E wherein the experimental power law exponent α ≈ 2.7. At the “knee” of the distribution, i.e. at energy E ∼ 1 PeV, there is a shift in the power law exponent to the value α ≈ 3.1. In [1], we had computed theoretically the ideal Bose index. Here we also compute the ideal Fermi statistical index so that they read together as: αBose = 2.701178 and αFermi = 3.151374 . (2) It would be well within experimental error to regard the knee as a crossover between statistics which in concrete physical evaporation terms merely means a crossover in the composition of cosmic ray emission winds blowing away from astrophysical sources. The critical values in Eq.(2) are ideal in the sense that the particles are ultrarelativistic E ≈ c|p| and noninteracting. One might ponder why a non-interacting theory is so close to experimental reality. The answer resides in the asymptotic freedom in the form of Feynman parton structure[6] of the ultrahigh energy tails of spectral functions. To describe cosmic ray sources in terms of thermal quantum field theoretical models, it is of some convenience to employ gamma and zeta function regulators whose definitions are reviewed in Sec.II wherein the ideal power law exponents are derived. That interactions apparently have little effect on the power law exponents would seem to imply that the quantum spectral functions are of the Feynman form[6] with Bose and Fermi operators being composites of quark operators. In the concluding Sec.III these points are qualitatively discussed. II. GAMMA AND ZETA REGULATORS A. Mathematical Details The mathematics of gamma and zeta regulators resides in the properties of classical special functions[7]. Starting with the statistical index η = 1 Bose, η = 0 Boltzmann and η = −1 Fermi, (3) IPPP/14/92, DCPT/14/184 Scalar Simplified Models for Dark Matter Matthew R. Buckley,1 David Feld,1 and Dorival Gon¸calves2 arXiv:1410.6497v1 [hep-ph] 23 Oct 2014 2 1 Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA Institute for Particle Physics Phenomenology, Department of Physics, Durham University, United Kingdom (Dated: October 27, 2014) We introduce a set of minimal simplified models for dark matter interactions with the Standard Model, connecting the two sectors via either a scalar or pseudoscalar particle. These models have a wider regime of validity for dark matter searches at the LHC than the effective field theory approach, while still allowing straightforward comparison to results from non-collider dark matter detection experiments. Such models also motivate dark matter searches in multiple correlated channels. In this paper, we constrain scalar and pseudoscalar simplified models with direct and indirect detection experiments, as well as from existing LHC searches with missing energy plus tops, bottoms, or jets, using the exact loop-induced coupling with gluons. This calculation significantly affects key differential cross sections at the LHC, and must be properly included. We make connections with the Higgs sector, and conclude with a discussion of future searches at the LHC. I. INTRODUCTION The case for the existence of dark matter is strong. Decades of evidence from multiple independent lines [1–4] reveal that this form of matter has a significant role in the composition and evolution of our Universe (for a review, see e.g., Ref. [5]). No particle in the Standard Model is a suitable candidate for dark matter and so we need new physics to explain it. Though we lack evidence of the nature of the dark sector, if particle dark matter has a mass at the TeV scale or lower and was ever in thermal equilibrium in the early Universe, we have good reason to expect interactions with the visible sector to be within reach of our present experiments. However, this is of course not guaranteed. Perhaps the best known example of such dark matter is a weakly-interacting massive particle which becomes a thermal relic with the appropriate energy density after freeze-out. This type of dark matter is realized in many extensions of the Standard Model introduced to solve other problems of a theoretical nature (e.g. Naturalness and Hierarchy). However, looking beyond this class of dark matter, even models of non-thermal dark matter often require significant annihilation cross sections into either the Standard Model or some hidden sector, so as not to overclose the Universe [6]. It is therefore well-motivated to search for dark sector particles in a range of experiments, including the Large Hadron Collider (LHC). When looking for dark matter, we can cast the experimental reach in terms of specific models of dark matter which are UV-complete. These models usually have a number of additional new particles with more significant interactions with the Standard Model than the dark matter itself. The canonical example of this sort is the supersymmetric neutralino, which is accompanied by a host of new charged and colored superpartners. Despite the advantage of UV-complete models, interpreting results in this way has some drawbacks: i) the results may be difficult to recast for new models; ii) correlating results with non-collider experiments may be very dependent on UV-complete parameters; iii) focusing on a specific high-energy model runs the risk of overlooking other experimentally interesting channels; and iv) tuning the experimental selection criteria could reduce the sensitivity to other types of dark matter. In order to approach the problem in a somewhat model-independent way while still allowing for comparison between different classes of experiments, it has been useful to present the results of experimental searches in an effective field theory (EFT) framework [7–9]. The EFT approach assumes contact term interactions between dark matter and SM particles with the particle(s) connecting the two sectors integrated out of the low-energy spectrum. The validity of the EFT approach diminishes in the regime where the momentum transfer cannot be neglected relative to the (unknown) mass of the heavy particles. For direct detection this condition is usually satisfied, as long as mediators are not extremely light, as the momentum scale is on the order of 10 keV. Indirect detection and thermal freeze-out involve the annihilation of non-relativistic dark matter and so the EFT is applicable as long as the mediator is significantly heavier than twice the dark matter mass, assuming no additional new particles in the theory [10]. However, when considering the production of dark matter at particle colliders through high pT visible particles recoiling against invisible dark matter [11–21], the momentum transfer in dark matter pair production events is large enough to render the EFT assumption invalid for a significant range of dark matter masses, couplings, and mediator masses [16, 18, 20, 22–29]. As the momentum flowing through the production diagram is proportional to both the transverse momentum of the dark matter particles (i.e. the missing transverse momentum, or MET) and the transverse momentum of recoiling visible particles required for the trigger, this issue will be even more pressing at the LHC Run-II, as the trigger requirements on MET and jet pT will be higher than those used in Run-I. Rather than viewing the invalidity of the EFT formalism as a drawback, it should be seen as an optimistic statement: if dark Prepared for submission to JHEP CP3-Origins-2014-033 DNRF90 DIAS-2014-33 IPPP/14/89 DCPT/14/178 arXiv:1410.6492v1 [hep-ph] 23 Oct 2014 Custodial Vector Model Diego Becciolini1 Diogo Buarque Franzosi1 Roshan Foadi2,3 Mads T. Frandsen1 Tuomas Hapola4 Francesco Sannino1 1 CP3 -Origins and the Danish Institute for Advanced Study, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark 2 Department of Physics, University of Jyv¨ askyl¨ a, P.O. Box 35, FI-40014, University of Jyv¨ askyl¨ a, Finland 3 Department of Physics & Helsinki Institute of Physics, P.O. Box 64, FI-000140, University of Helsinki, Finland 4 Institute for Particle Physics Phenomenology, Durham University, South Road, Durham DH1 3LE, UK Abstract: We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a SU (2)L × SU (2)R spectral global symmetry. This symmetry partially protects the electroweak S-parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum and interactions with the standard model fields lead to distinct signatures at the LHC in the diboson, dilepton and associated Higgs channels. arXiv:1410.6489v1 [hep-ph] 23 Oct 2014 NEW RESULTS IN THE QUANTUM STATISTICAL APPROACH TO PARTON DISTRIBUTIONS 1 JACQUES SOFFER Physics Department, Temple University, 1835 N, 12th Street, Philadelphia, PA 19122-6082, USA E-mail: [email protected] CLAUDE BOURRELY Aix-Marseille Universit´e, D´epartement de Physique, Facult´e des Sciences site de Luminy, 13288 Marseille, Cedex 09, France E-mail: [email protected] FRANCO BUCCELLA INFN, Sezione di Napoli, Via Cintia, Napoli, I-80126, Italy E-mail: [email protected] Abstract We will describe the quantum statistical approach to parton distributions allowing to obtain simultaneously the unpolarized distributions and the helicity distributions. We will present some recent results, in particular related to the nucleon spin structure in QCD. Future measurements are challenging to check the validity of this novel physical framework. Key words: Gluon polarization; Proton spin; Statistical distributions PACS numbers: PACS numbers: 12.40.Ee, 13.60.Hb, 13.88.+e, 14.70.Dj 1 Invited talk presented by J. Soffer at the ”‘QCD Evolution Workshop”’, May 12 16, 2014, Santa Fe, New Mexico, USA (to be published in World Scientific Conference Proceedings) Prepared for submission to JHEP NIKHEF 2014-043 arXiv:1410.6483v1 [hep-ph] 23 Oct 2014 Resummation of Double-Differential Cross Sections and Fully-Unintegrated Parton Distribution Functions Massimiliano Procura,a Wouter J. Waalewijn,b,c Lisa Zeuneb a Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, CH-3012 Bern, Switzerland b ITFA, University of Amsterdam, Science Park 904, 1018 XE, Amsterdam, The Netherlands c Nikhef, Theory Group, Science Park 105, 1098 XG, Amsterdam, The Netherlands E-mail: [email protected], [email protected], [email protected] Abstract: LHC measurements involve cuts on several observables, but resummed calculations are mostly restricted to single variables. We show how the resummation of a class of double-differential measurements can be achieved through an extension of Soft-Collinear Effective Theory (SCET). A prototypical application is pp → Z + 0 jets, where the jet veto is imposed through the beam thrust event shape T , and the transverse momentum pT of the 1/2 Z boson is measured. A standard SCET analysis suffices for pT ∼ mZ T 1/2 and pT ∼ T , but additional collinear-soft modes are needed in the intermediate regime. We show how to match the factorization theorems that describe these three different regions of phase space, and discuss the corresponding relations between fully-unintegrated parton distribution functions, soft functions and the newly defined collinear-soft functions. The missing ingredients needed at NNLL/NLO accuracy are calculated, providing a check of our formalism. We also revisit the calculation of the measurement of two angularities on a single jet in JHEP 1409 (2014) 046, finding a correction to their conjecture for the NLL cross section at O(αs2 ). Lecture notes on “Quantum chromodynamics and statistical physics”∗ St´ephane Munier arXiv:1410.6478v1 [hep-ph] 23 Oct 2014 ´ Centre de physique th´eorique, Ecole Polytechnique, CNRS, Palaiseau, France. Abstract The concepts and methods used for the study of disordered systems have proven useful in the analysis of the evolution equations of quantum chromodynamics in the high-energy regime: Indeed, parton branching in the semi-classical approximation relevant at high energies is a peculiar branching-diffusion process, and parton branching supplemented by saturation effects (such as gluon recombination) is a reaction-diffusion process. In these lectures, we first introduce the basic concepts in the context of simple toy models, we study the properties of the latter, and show how the results obtained for the simple models may be taken over to quantum chromodynamics. Contents 1 Branching random walks and the Fisher-Kolmogorov-Petrovsky-Piscounov equation 3 1.1 Brownian motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Branching random walk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Solving the FKPP equation 2.1 Heuristic analysis of the equation . . . . . . . . . . . . . . . 2.2 Bramson’s theorem: traveling waves . . . . . . . . . . . . . 2.3 Heuristic derivation of the properties of the traveling waves 2.3.1 Asymptotic shape and velocity . . . . . . . . . . . . 2.3.2 Finite-time corrections . . . . . . . . . . . . . . . . . 2.4 “Dual” interpretation of the solution to the FKPP equation 2.5 Generalization to other branching-diffusion processes . . . . . . . . . . . . . . . . . . . . . . . . . 3 Applications to QCD 3.1 QCD evolution at very high energies . . . . . . . . . . . . . . . . 3.2 QCD evolution as a branching random walk . . . . . . . . . . . . 3.3 Mapping the Balitsky-Kovchegov equation to the FKPP equation 3.3.1 Calculation of the eigenvalues of the BFKL kernel . . . . 3.3.2 Compact expression for the BFKL and BK equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 13 14 15 15 16 18 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 22 24 26 26 28 . . . . . . . . . . . . . . ∗ Lectures given at the “Huada school on QCD”, Central China Normal University, Wuhan, China, June 2-13, 2014. 1 Deuteron Electro-Disintegration at Very High Missing Momenta arXiv:1410.6770v1 [nucl-ex] 24 Oct 2014 K. Aniol California State University L.A. F. Benmokhtar Carnegie Mellon University W.U. Boeglin (spokesperson), P.E. Markowitz, B.A. Raue, J. Reinhold and M. Sargsian Florida International University C. Keppel, M. Kohl Hampton University D. Gaskell, D. Higinbotham, M. K. Jones (co-spokesperson),G. Smith and S. Wood Jefferson Lab S. Jeschonnek Ohio State University J. W. Van Orden Old Dominion University G. Huber University of Regina E. Piasetzky, G. Ron, R. Shneor Tel-Aviv University H. Bitao Lanzhou University X. Jiang, A. Puckett Los Alamos National Laboratory 1 Abstract We propose to measure the D(e,e0 p)n cross section at Q2 = 4.25 (GeV/c)2 and xbj = 1.35 for missing momenta ranging from pm = 0.5 GeV/c to pm = 1.0 GeV/c expanding the range of missing momenta explored in the Hall A experiment (E01-020). At these energy and momentum transfers, calculations based on the eikonal approximation have been shown to be valid and recent experiments indicated that final state interactions are relatively small and possibly independent of missing momenta. This experiment will provide for the first time data in this kinematic regime which are of fundamental importance to the study of short range correlations and high density fluctuations in nuclei. The proposed experiment could serve as a commissioning experiment of the new SHMS together with the HMS in Hall C. A total beam time of 21 days is requested. 3 version 1.0 Estimate of cold nuclear matter effects on bottom production in d+Au collisions at √ sN N = 200 GeV Daniel Kikola1 and Andrzej Lipiec1 1 Warsaw University of Technology, Warsaw, Poland (Dated: October 27, 2014) We investigate modification of the bottom quark production due to cold nuclear matter effects √ (CNM) at mid-rapidity in d+Au collisions at sN N = 200 GeV at RHIC. Our results indicate that bottom production is not suppressed due to CNM effects in those collisions. We also found that shadowing and initial kT breadboarding for charm quarks explains at low pT (pT < 3 GeV/c) the √ enhancement of heavy flavor decay electron yield in d+Au collisions at sN N = 200 GeV compared to p+p. PACS numbers: 13.20.He, 14.40.Nd, 21.65.-f,25.40.-h arXiv:1410.6503v1 [nucl-ex] 23 Oct 2014 I. INTRODUCTION High energy heavy ion collisions provide an opportunity to create in a laboratory a Quark Gluon Plasma, QGP, a state of matter with quark and gluon degree of freedom. Charm and bottom quarks are important probes of the properties of the QGP because they are created in the initial scatterings with large momentum transfer and are expected to interact with the QGP differently than light quarks (see Ref. [1] and references therein). For instance, studies of the heavy quark energy loss in nucleus-nucleus collisions could provide information about transport properties of the created nuclear medium. It is important to measure charm and bottom production separately in ˚ a collisions to have a full picture of energy loss for light and heavy quarks. This was a major motivation for recently completed upgrades at the STAR and PHENIX experiments at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. These upgrades include a micro-vertexing detectors: Heavy Flavor Tracker (HFT) at STAR and Silicon Vertex Tracker (VTX) and Forward Silicon Vertex Detector (FVTX) at PHENIX, which allow measurement of charm and bottom production. Charm will be measured via direct reconstruction of hadronic decays of D mesons. Electrons from semi-leptonic decays of bottom hadrons (noted here as b → e) are the most feasible tools for bottom studies. STAR and PHENIX collected large data √ samples of Au+Au collisions at sN N = 200 GeV which will allow precise measurement of heavy quark production and their nuclear modification factors. For interpretation of these results, it is important to have an estimate of so-called cold nuclear matter (CNM) effects for c and b quarks i.e. modification of production not related to the QGP formation. Experimentally we address these effects by measuring particle production in p+A or d+Au interactions. Such data for b and c quarks are not available so far (charm and bottom separation in p+A will be possible in 2016, after p+A run at RHIC). However, it is crucial to have an estimate of CNM effects on bottom quark production when the first precise Au+Au data are available in 2015. Moreover, current data for electrons from semi-leptonic decays of heavy flavor hadrons, eHF , show an enhancement of the production in central and minimum bias d+Au collisions at mid-rapidity at RHIC [2]. Recent observations of collective behavior of light hadrons in d+Au collisions at RHIC and p+A at LHC triggered speculations that this enhancement is an indication of collective phenomena (radial flow) for heavy quarks in d+Au [3]. However, this enhancement could be also owing to the CNM effects. In this paper we estimate the modification of the bottom quark production due to cold nuclear matter effects at top RHIC energy. First, we make a minimal set of assumptions about those effects for charm and we simulate electrons from charmed meson decays (c → e) in d+Au reactions. We consider initial transverse momentum (kT ) broadening of partons and modification of the parton distribution function in a nucleon in a nucleus compared to a free proton (so called shadowing). Then we simulate c → e in d+Au with those CNM included √ using measured charm pT spectrum in p+p collisions at s = 200 GeV as an input. Then we subtract c → e contribution from eHF yield measured by PHENIX collaboration to obtain electrons from bottom hadron decays. We also investigate if the eHF enhancement can be explained by established cold nuclear matter effects namely kT broadening and shadowing. II. SIMULATION SETUP We use√charm differential cross section in p+p collisions at s = 200 GeV as input in our simulations. We construct the input spectra by combining the published STAR data [4] and recent preliminary results [5]. The pT spectrum is parametrized with a Levy function m2T −mD −n (n−1)(n−2) f (pT ) = A nT (nT ) , where A, +mD (n−2)) (1 + nT T and n are free parameters, m = 1.86484 GeV/c2 D p is D0 mass and mT = m2D + pT 2 . We chose this parametrization because it represents charm pT spectrum in a broad pT range (1-18 GeV/c) in p+p colli-

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