Geometrical Scaling of Direct Photons in Relativistic Heavy Ion and d+Au Collisions

Abstract

In this paper, we show that multiplicity spectra of direct photons in A+A and d+Au collisions at different centrality classes and different energies exhibit geometrical scaling, {\em i.e.}, they depend on a specific combination of number of participants $N_{\mathrm{part}}$, collisions energy $W$, and transverse momentum $p_T$ -- called saturation scale -- rather than on all these three variables separately. In particular, the dependence on the geometry of collisions encoded in the dependence on $N_{\mathrm{part}}$ is in agreement with the expectations based on the Color Glass Condensate theory.

arXiv comment9 pages, 6 figures

References in corpus (29)

• Operator expansion for high-energy scattering
• Hadron production in nuclear collisions at RHIC and high density QCD
• Geometric scaling for the total gamma^* p cross section in the low x region
• The production of photons in relativistic heavy-ion collisions
• The Energy Dependence of the Saturation Momentum
• Geometric Scaling above the Saturation Scale
• Geometric scaling as traveling waves
• Direct photon production in Pb-Pb collisions at $\sqrt{s_\rm{NN}}$ = 2.76 TeV
• Effective kinetic description of event-by-event pre-equilibrium dynamics in high-energy heavy-ion collisions
• How Protons Shatter Colored Glass
• Investigations of anisotropic flow using multi-particle azimuthal correlations in pp, p-Pb, Xe-Xe, and Pb-Pb collisions at the LHC
• Measurement of Direct Photons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Multi-messenger heavy-ion collision physics
• Saturation and Scaling of Multiplicity, Mean p_T and p_T Distributions from 200 GeV < sqrt{s} < 7 TeV - Addendum
• Beam-energy and centrality dependence of direct-photon emission from ultra-relativistic heavy-ion collisions
• Geometric scaling and QCD evolution
• Production of Photons and Dileptons in the Glasma
• Correlated long-range mixed-harmonic fluctuations measured in $pp$, $p$+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector
• Geometric Scaling from GLAP evolution
• Geometrical Scaling of Direct-Photon Production in Hadron Collisions from RHIC to the LHC
• A Tale of Tails: Photon Rates and Flow in Ultra-Relativistic Heavy Ion Collisions
• Geometrical Scaling in Inelastic Inclusive Particle Production at the LHC
• Benchmarking a Non-Equilibrium Approach to Photon Emission in Relativistic Heavy-Ion Collisions
• Low-momentum direct photon measurement in Cu$+$Cu collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Photons from thermalizing matter in heavy ion collisions
• PHENIX measurements of low momentum direct photon radiation
• A Phenomenological Model of the Glasma and Photon Production
• Scaling properties of direct photon yields in heavy ion collisions
• Geometrical scaling of prompt photons in heavy ion collisions