Hydrodynamic description of direct photon spectra and elliptic flow in Pb+Pb collisions at LHC

Abstract

In high energy heavy ion collisions a new state of matter, the strongly coupled quark gluon plasma is formed that exhibits the similar properties as our Universe had just a couple of microseconds after the Big Bang, hence such collisions are usually referred as Little Bangs. Subsequent investigations showed that the created medium is a nearly perfect fluid whose time evolution can be described by hydrodynamic models. The distribution of the hadrons that are created in the freeze-out after a rapid expansion carry information about the final state. On the other hand, with penetrating probes, e.g., with direct photons, one can model the time evolution of the quark gluon plasma. In this paper, we present a hydrodynamic model that was inspired by an analytical solution of relativistic hydrodynamics, calculate the invariant transverse momentum spectrum and the elliptic flow of direct photons and compare our results to LHC ALICE data to obtain the value of the model parameters. Based on the the results we give an estimation for the initial temperature of the plasma.

arXiv comment2 figures, 11 pages

References in corpus (26)

• The QCD equation of state with dynamical quarks
• Photon Emission from Quark-Gluon Plasma: Complete Leading Order Results
• Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature
• The production of photons in relativistic heavy-ion collisions
• Description of the RHIC p_T-spectra in a thermal model with expansion
• Conformal anomaly as a source of soft photons in heavy ion collisions
• Hadronic resonance production and interaction in partonic and hadronic matter in EPOS3 with and without the hadronic afterburner UrQMD
• Production and Elliptic Flow of Dileptons and Photons in the semi-Quark Gluon Plasma
• Update of the Hagedorn mass spectrum
• Hadronic and partonic sources of direct photons in relativistic heavy-ion collisions
• Multi-messenger heavy-ion collision physics
• Particle Interferometry from 40 MeV to 40 TeV
• Simple solutions of relativistic hydrodynamics for systems with ellipsoidal symmetry
• Different Hagedorn temperatures for mesons and baryons from experimental mass spectra, compound hadrons, and combinatorial saturation
• Exact solutions of relativistic perfect fluid hydrodynamics for a QCD equation of state
• The Hagedorn temperature Revisited
• Observables from a solution of 1+3 dimensional relativistic hydrodynamics
• Universal scaling of the elliptic flow data at RHIC
• Universal scaling of the elliptic flow at RHIC
• Does the empirical meson spectrum support the Hagedorn conjecture?
• Accelerating hydrodynamic description of pseudorapidity density and the initial energy density in p+p, Cu+Cu, Au+Au, and Pb+Pb collisions at RHIC and LHC
• Lifetime estimations from RHIC Au+Au data
• Measuring initial temperature through photon to dilepton ratio in heavy ion collision
• Initial temperature and EoS of quark matter from direct photons
• Electromagnetic signals from Au+Au collisions at RHIC energy, $\sqrt{s_{NN}}$=200 GeV and Pb+Pb collisions at LHC energy, $\sqrt{s_{NN}}$=2.76 TeV
• Describing the Thermal Radiation in $Au+Au$ Collisions at $\sqrt{s_{NN}}=$200 GeV by an Analytic Solution of Relativistic Hydrodynamics