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

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 the 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 $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV. We test the sensitivity of the results to the choice of equilibration times, 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 $p_T$-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.

27 pages, 13 figures, v3: minor corrections, to match published version

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• Uniform description of bulk observables in the hydrokinetic model of A+A collisions at RHIC and LHC
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• Thermal photon $v_2$ with slow quark chemical equilibration
• Universal Parametrization of Thermal Photon Rates in Hadronic Matter
• Longitudinal fluid dynamics for ultrarelativistic heavy-ion collisions
• Quarks Production in the Quark-Gluon Plasma Created in Relativistic Heavy Ion Collisions
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Cited by in corpus (23)

• Multi-messenger heavy-ion collision physics
• The Present and Future of QCD
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• Ellipticity of photon emission from strongly magnetized hot QCD plasma
• The emission of electromagnetic radiation from the early stages of relativistic heavy-ion collisions
• Holographic Photon Production in Heavy Ion Collisions
• Excluded-volume effects for a hadron gas in Yang-Mills theory
• Prompt, pre-equilibrium, and thermal photons in relativistic nuclear collisions
• Probing the spacetime evolution of heavy ion collisions with photons and dileptons
• Spectra and elliptic flow of thermal photons from full overlap U+U collisions at RHIC
• 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
• Decoding the flow evolution in Au+Au reactions at $1.23A$ GeV using hadron flow correlations and dileptons
• Directed flow in asymmetric nucleus-nucleus collisions and the inverse Landau-Pomeranchuk-Migdal effect
• Direct Photons in Hydrodynamic Modeling of Relativistic Nuclear Collisions
• Review of opportunities at the HESR-Collider with PANDA at FAIR
• Photon and dilepton emission anisotropy for a magnetized quark-gluon plasma
• Quark flavor equilibration of the quark-gluon plasma
• An Initial State with Shear in Peripheral Heavy Ion Collisions
• Impact of residual contamination on inclusive and direct photon flow
• Photon emissivity in the vicinity of a critical point - A case study within the quark meson model
• Hydrodynamic model of heavy-ion collisions with low momentum components
• Finite-Density Dynamics of Chemically Equilibrating QGP in Conformal Gubser Flow and Hard Thermal Photon Production