Electromagnetic recombination spectra at the quark-hadron phase transition

Abstract

When quarks hadronize, they accelerate. Because they carry electric charge, they must radiate light as they accelerate and hadronize. This is true not only in jets but also in heavy ion collisions, where a thermalized plasma of quarks and gluons cools into a gas of hadrons. First, direct emission of photons from two quarks coalescing into pions is calculated using the quark-meson model. The yield of final-state photons to pions is found to be about $e^2/g_{\pi qq}^2$, which is on the order of a percent. Second, the yield of photons from the decay of highly excited color singlets, which may exist ephemerally during hadronizaton, is estimated. Because these contributions occur late in the reaction, they should carry significant elliptic flow, which may help explain the large observed flow of direct photons at RHIC by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). The enhanced emission also helps explain PHENIX's surprisingly large observed $\gamma /\pi$ ratio.

18 pages, 6 figures

References in corpus (4)

• The QCD equation of state with dynamical quarks
• The production of photons in relativistic heavy-ion collisions
• Dilepton and photon production in the presence of a nontrivial Polyakov loop
• Photon production from gluon mediated quark-anti-quark annihilation at confinement

Cited by in corpus (5)

• Probing the spacetime evolution of heavy ion collisions with photons and dileptons
• Radiative hadronization: Photon emission at hadronization from quark-gluon plasma
• Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model
• Electromagnetic Radiation from QCD Matter: Theory Overview
• Photon spectra and anisotropic flow in heavy ion collisions at the top RHIC energy within the integrated hydrokinetic model with photon hadronization emission