Electromagnetic probes of a pure-glue initial state in nucleus-nucleus collisions at energies available at the CERN Large Hadron Collider

V. Vovchenko, Iu. A. Karpenko, M. I. Gorenstein, L. M. Satarov, I. N. Mishustin, B. Kämpfer, and H. Stoecker
Phys. Rev. C 94, 024906 – Published 9 August 2016

Abstract

Partonic matter produced in the early stage of ultrarelativistic nucleus-nucleus collisions is assumed to be composed mainly of gluons, and quarks and antiquarks are produced at later times. To study the implications of such a scenario, the dynamical evolution of a chemically nonequilibrated system is described by ideal (2+1)-dimensional hydrodynamics with a time dependent (anti)quark fugacity. The equation of state interpolates linearly between the lattice data for the pure gluonic matter and the lattice data for the chemically equilibrated quark-gluon plasma. The spectra and elliptic flows of thermal dileptons and photons are calculated for central Pb+Pb collisions at the CERN Large Hadron Collider energy of sNN=2.76 TeV. We test the sensitivity of the results to the choice of equilibration time, including also the case where the complete chemical equilibrium of partons is reached already at the initial stage. It is shown that a suppression of quarks at early times leads to a significant reduction of the yield of the thermal dileptons, but only to a rather modest suppression of the pT distribution of direct photons. It is demonstrated that an enhancement of photon and dilepton elliptic flows might serve as a promising signature of the pure-glue initial state.

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  • Received 27 April 2016

DOI:https://doi.org/10.1103/PhysRevC.94.024906

©2016 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

Authors & Affiliations

V. Vovchenko1,2,3, Iu. A. Karpenko4,5, M. I. Gorenstein1,4, L. M. Satarov1,6, I. N. Mishustin1,6, B. Kämpfer7,8, and H. Stoecker1,2,9

  • 1Frankfurt Institute for Advanced Studies, D-60438 Frankfurt, Germany
  • 2Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
  • 3Taras Shevchenko National University of Kiev, 03022 Kiev, Ukraine
  • 4Bogolyubov Institute for Theoretical Physics, 03680 Kiev, Ukraine
  • 5INFN - Sezione di Firenze, I-50019 Sesto Fiorentino (Firenze), Italy
  • 6National Research Center “Kurchatov Institute”, 123182 Moscow, Russia
  • 7Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany
  • 8Technische Universität Dresden, Institut für Theoretische Physik, D-01062 Dresden, Germany
  • 9GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany

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Issue

Vol. 94, Iss. 2 — August 2016

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