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)
Mr
Patrick Huck
(LBNL/CCNU)
5/19/14, 11:00โฏAM
Electromagnetic Probes
Contributed Talk
Bulk-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...
Markus Kohler
(GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))
5/19/14, 11:20โฏAM
Electromagnetic Probes
Contributed Talk
Electromagnetic 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...
Mr
Ismail Zahed
(Stony Brook University)
5/19/14, 11:40โฏAM
Electromagnetic Probes
Contributed Talk
I 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.
Rupa Chatterjee
5/19/14, 12:00โฏPM
Electromagnetic Probes
Contributed Talk
Thermal 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...
Chun Shen
(Ohio State University)
5/19/14, 12:20โฏPM
Electromagnetic Probes
Contributed Talk
Photons 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...
Shu Lin
(RIKEN BNL)
5/19/14, 12:40โฏPM
Electromagnetic Probes
Contributed Talk
Experimental 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...
Sanshiro Mizuno
(University of Tsukuba (JP))
5/19/14, 2:20โฏPM
Collective Dynamics
Contributed Talk
Soft 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...
Chi Yang
(USTC/BNL)
5/19/14, 2:40โฏPM
Electromagnetic Probes
Contributed Talk
One 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...
Friederike Bock
(Ruprecht-Karls-Universitaet Heidelberg (DE))
5/19/14, 3:00โฏPM
Electromagnetic Probes
Contributed Talk
Unlike 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...
Prof.
Ralf Rapp
(Texas A&M University)
5/19/14, 3:20โฏPM
Electromagnetic Probes
Contributed Talk
A 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...
Gojko Vujanovic
(McGill University)
5/19/14, 3:40โฏPM
Electromagnetic Probes
Contributed Talk
Much 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...
Dr
Ahmed M. Hamed
(University of Mississippi, Texas A&M University)
5/19/14, 4:30โฏPM
Electromagnetic Probes
Contributed Talk
Many 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...
Frasher Loshaj
(Stony Brook University)
5/19/14, 4:50โฏPM
Electromagnetic Probes
Contributed Talk
Soft 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...
Anna Zsigmond
(Wigner RCP, Budapest (HU))
5/19/14, 5:10โฏPM
Electromagnetic Probes
Contributed Talk
The 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...
Iwona Grabowska-Bold
(AGH University of Science and Technology (PL))
5/19/14, 5:30โฏPM
Collective Dynamics
Contributed Talk
Photons 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...
Gianluca Usai
(Universita e INFN (IT))
5/19/14, 5:50โฏPM
Electromagnetic Probes
Contributed Talk
The 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...
Claudia Hoehne
(GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))
5/19/14, 6:10โฏPM
Future Experimental Facilities, Upgrades, and Instrumentation
Contributed Talk
The 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...
