Conveners
Electromagnetic probes: 1
- Charles Gale (McGill University)
Electromagnetic probes: 2
- Thomas Peitzmann (University of Utrecht (NL))
Electromagnetic probes: 3
- Joachim Stroth (Goethe-University and GSI)
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Mr Patrick Huck (LBNL/CCNU)19/05/2014, 11:00Electromagnetic ProbesContributed TalkBulk-penetrating dielectrons allow for the extraction of direct information from all stages of a heavy ion collision as they serve as electromagnetic probes with negligible final-state interactions. The completion of the Barrel Time-of-Flight detector (TOF) in 2010 has allowed the Solenoid Tracker At RHIC (STAR) to play a unique role in the study of dielectron production with excellent...Go to contribution page
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Markus Kohler (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))19/05/2014, 11:20Electromagnetic ProbesContributed TalkElectromagnetic probes are excellent messengers from the hot and dense medium created in ultra-relativistic heavy-ion collisions. Since leptons do not interact strongly, their spectra reflect the entire space-time evolution of a collision. The surrounding medium can lead to modifications of the dielectron production rate. To quantify modifications in heavy-ion collisions, measurements in...Go to contribution page
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Mr Ismail Zahed (Stony Brook University)19/05/2014, 11:40Electromagnetic ProbesContributed TalkI will discuss the general features of the electromagnetic radiation from QCD matter using spectral functions in the hadronic phase and the OPE expansion in the partonic phase, and use them to analyze current di-lepton and photon emissions at collider energies both at RHIC and LHC. The large low mass di-lepton enhancement and photon v2 will be addressed.Go to contribution page
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Rupa Chatterjee19/05/2014, 12:00Electromagnetic ProbesContributed TalkThermal photon $v_3$ is calculated for 0--40% central collisions of Pb nuclei at LHC from event-by-event ideal hydrodynamic model [1]. The differential triangular flow parameter $v_3(p_T)$ calculated with respect to the participant plane (PP) is found to be non-zero, positive, and shows similar qualitative nature to the elliptic flow parameter $v_2(p_T)$ [2]. At $p_T=$ 1 GeV $v_3$(PP) is...Go to contribution page
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Chun Shen (Ohio State University)19/05/2014, 12:20Electromagnetic ProbesContributed TalkPhotons are believed to be clean and penetrating probes of the medium created in ultra-relativistic heavy-ion collisions. The thermal photon spectrum and its anisotropy coefficients, $v_n$, are known to be very sensitive to the thermalization time, the specific shear viscosity, the equation of state of produced matter, and the initial state fluctuations [1,2]. In this talk, we will present...Go to contribution page
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Shu Lin (RIKEN BNL)19/05/2014, 12:40Electromagnetic ProbesContributed TalkExperimental measurements of photon collective flow have obtained v2 comparable to those of hadrons. This favors a scenario of hadron dominated medium in photon production. A realistic calculation of photon rate in QGP phase is important to scrutinize this scenario. Fire ball produced in RHIC and LHC is close to semi-QGP which has a non-trivial value of Polyakov loop. We calculated the photon...Go to contribution page
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Sanshiro Mizuno (University of Tsukuba (JP))19/05/2014, 14:20Collective DynamicsContributed TalkSoft photons are of particular interest since they are unmodified once produced, and thus carry information about the space-time thermal properties of the medium. We present new results on the centrality dependence of soft single photons in Au$+$Au collisions, down to $p_T = 400$ MeV/$c$ via photon conversions to $e^+e^-$ pairs. These measurements provide stringent tests of the...Go to contribution page
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Chi Yang (USTC/BNL)19/05/2014, 14:40Electromagnetic ProbesContributed TalkOne important physics goal of ultra-relativistic heavy-ion collisions is to study the fundamental properties of a hot, dense medium created in these collisions. This medium is expected to emit thermal radiation which is in the form of direct photons and dileptons. Once produced, photons and leptons traverse the strongly interacting medium with minimal interactions. The fully...Go to contribution page
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Friederike Bock (Ruprecht-Karls-Universitaet Heidelberg (DE))19/05/2014, 15:00Electromagnetic ProbesContributed TalkUnlike hadrons, direct photons are produced in all stages of a nucleus-nucleus collision and therefore test our understanding of the space-time evolution of the produced medium. Of particular interest are so-called thermal photons expected to be produced in a quark-gluon plasma and the subsequent hadron gas. The transverse momentum spectrum of thermal photons carries information...Go to contribution page
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Prof. Ralf Rapp (Texas A&M University)19/05/2014, 15:20Electromagnetic ProbesContributed TalkA relatively small spectral slope and large elliptic flow of direct photons measured at RHIC and LHC has reignited the discussion of thermal photons as a probe of the quark-gluon plasma (QGP). We present a systematic discussion of the macro- and micro-physics that figures into calculating thermal emission spectra. For the bulk medium we compare the temperature and flow evolution in...Go to contribution page
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Gojko Vujanovic (McGill University)19/05/2014, 15:40Electromagnetic ProbesContributed TalkMuch work has been devoted to the determination of an effective value of the shear viscosity coefficient from analyses of the hadronic final states in relativistic heavy-ion collisions. Electromagnetic radiation, however, constitutes a class of complementary and penetrating probes that are sensitive to the entire space-time history of nuclear collisions including its very early stages. We show...Go to contribution page
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Dr Ahmed M. Hamed (University of Mississippi, Texas A&M University)19/05/2014, 16:30Electromagnetic ProbesContributed TalkMany observations have indicated that the fragmentation functions in nucleus-nucleus collisions are softened compared to that in proton-proton collisions. Different theoretical models have been proposed in order to describe the observed phenomena. For a deeper insight into the underlying physics and better constraints for the extracted parameters of the medium formed in nucleus-nucleus...Go to contribution page
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Frasher Loshaj (Stony Brook University)19/05/2014, 16:50Electromagnetic ProbesContributed TalkSoft photons produced in heavy ion collisions are an important tool in probing the properties of the quark-gluon plasma. For this purpose, it is crucial to understand the background - soft photons produced in elementary collisions. Low theorem states that soft photon production in hadron collisions is dominated by Bremsstrahlung off charged initial and final state hadrons. Surprisingly, almost...Go to contribution page
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Anna Zsigmond (Wigner RCP, Budapest (HU))19/05/2014, 17:10Electromagnetic ProbesContributed TalkThe weak bosons, Z and W, do not participate in the strong interaction, and thus constitute clean probes of the initial state of nuclear collisions. Detected trough their leptonic decay channels, they provide constraints on the nuclear parton distribution functions (PDF). In particular the W boson proves a unique constraint on the sea quark distributions. We report on CMS measurements of...Go to contribution page
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Iwona Grabowska-Bold (AGH University of Science and Technology (PL))19/05/2014, 17:30Collective DynamicsContributed TalkPhotons and weak bosons do not interact strongly, and thus their production yields provide direct tests of binary collision scaling, and in addition should be sensitive to the nuclear modification of parton distribution functions (nPDFs). Proton-lead collisions also provide an excellent opportunity to test nPDFs in a less dense environment than lead-lead, along with useful forward backward...Go to contribution page
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Gianluca Usai (Universita e INFN (IT))19/05/2014, 17:50Electromagnetic ProbesContributed TalkThe structure of the QCD phase diagram in the region of moderate temperature and high baryon density is still almost unexplored. In this regime, the QGP and hadronic phases should be separated by a first order transition region. On the other hand, for sufficiently low baryonic chemical potential a simple cross-over is expected. The end point of the first order transition region is the so...Go to contribution page
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Claudia Hoehne (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))19/05/2014, 18:10Future Experimental Facilities, Upgrades, and InstrumentationContributed TalkThe Compressed Baryonic Matter (CBM) experiment at the upcoming Facility for Antiproton and Ion Research (FAIR) will explore the phase diagram of nuclear matter at very high net-baryon densities and moderate temperatures in nucleus-nucleus collisions at beam energies up to 45 A GeV . One of the key diagnostic probes of strongly-interacting matter at extreme conditions are dileptons. Dilepton...Go to contribution page