Single photons from relativistic collision of lead nuclei at CERN SPS: A reanalysis

Abstract

We present a reanalysis of single photon production from relativistic collision of lead nuclei at CERN SPS measured by the WA98 experiment. The refinements include use of iso-spin and shadowing corrected NLO pQCD treatment for prompt photon production using an optimized scale for factorization, renormalization, and fragmentation and use of hydrodynamics suited for non-central collisions along with a well tested equation of state admitting a quark-hadron phase transition. A quantitative explanation of the data requires a large initial temperature (at a small formation time of about 0.2 fm/$c$) and a moderate increase in the prompt yield which could perhaps be attributed to the Cronin effect in nuclei. The data can also be explained using a moderate initial temperature (at a formation time of about 1 fm/$c$) with a very large $K$-factor multiplying the prompt yield. We show that different initial times give rise to different values for the elliptic flow parameter $v_2$ for thermal photons. We also show that a measurement of $v_2$ for thermal photons could also distinguish between the scenarios with or without a phase transition.

arXiv comment10 pages, 13 figures

References in corpus (33)

• Anisotropic transverse flow and the quark-hadron phase transition
• Photon Emission from Quark-Gluon Plasma: Complete Leading Order Results
• Hadronic Production of Thermal Photons
• Multiplicity scaling in ideal and viscous hydrodynamics
• A new critical study of photon production in hadronic collisions
• Observation of Direct Photons in Central 158 A GeV 208Pb+208Pb Collisions
• High energy photons from passage of jets through quark gluon plasma
• Elliptic flow of thermal photons in relativistic nuclear collisions
• A critical phenomenological study of inclusive photon production in hadronic collisions
• Electromagnetic radiation from nuclear collisions at RHIC energies
• Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV
• Effects of Parton Intrinsic Transverse Momentum on Photon Production in Hard-Scattering Processes
• Indications of suppressed high p_T hadron production in nucleus-nucleus collisions at CERN-SPS
• Photons from Pb-Pb Collisions at CERN SPS
• Photon emission in heavy ion collisions at the CERN SPS
• Radiation of single photons from $Pb+Pb$ collisions at the CERN SPS and quark hadron phase transition
• Elliptic flow of thermal dileptons in relativistic nuclear collisions
• Elliptic flow of thermal photons and formation time of quark gluon plasma at RHIC
• Light from Cascading Partons in Relativistic Heavy-Ion Collisions
• Centrality Dependence of Direct Photons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Measurement of direct photon production at Tevatron fixed target energies
• Direct photons from relativistic heavy-ion collisions
• Nuclear Broadening Effects on Hard Prompt Photons at Relativistic Energies
• Dynamics of the Landau-Pomeranchuk-Migdal Effect in Au+Au Collisions at 200 AGeV
• Intensity interferometry of thermal photons from relativistic heavy ion collisions
• Elliptic flow of thermal photons and dileptons
• Scaling of single photon production in hadronic collisions
• Photons from nuclear collisions at RHIC energies
• Semi-hard scattering of partons at SPS and RHIC: A study in contrast
• High pt Measurements at the CERN SPS
• Pre-equilibrium dileptons look thermal
• Are High-pT Pions Suppressed in Pb+Pb Collisions at sqrt(sNN) = 17.3 GeV?
• Search for direct photons in p+Pb and p+C collisions at sqrt(sNN) = 17.4 GeV

Cited by in corpus (9)

• Identified particle production, azimuthal anisotropy, and interferometry measurements in Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV
• Exploring the QCD landscape with high-energy nuclear collisions
• Electromagnetic probes
• Photon production from Pb+Pb collisions at {$\sqrt{s_{\mathrm{NN}}}$} = 5.02 TeV at LHC and at {$\sqrt{s_{\mathrm{NN}}}$} = 39 TeV at FCC
• Radial Flow from Electromagnetic Probes and Signal of Quark Gluon Plasma
• Interference of thermal photons from quark and hadronic phases in relativistic collisions of heavy nuclei
• Equation of state of strongly interacting matter: spectra for thermal particles and intensity correlation of thermal photons
• A Reanalysis of Single Photon Data at CERN SPS
• Photon and Eta Production in p+Pb and p+C Collisions at sqrt{sNN} = 17.4 GeV