Effects of initial-state nucleon shadowing on the elliptic flow of thermal photons

Recently the effect of nucleon shadowing on the Monte Carlo–Glauber initial condition was studied and its role on the centrality dependence of elliptic flow ($v_2$) and fluctuations in initial eccentricity for different colliding nuclei were explored. It was found that the results with shadowing effects are closer to the QCD-based dynamical model as well as to the experimental data. Inspired by this outcome, in this work we study the transverse momentum ($p_T$) spectra and elliptic flow of thermal photons for $\mathrm{Au}+\mathrm{Au}$ collisions at the BNL Relativisitic Heavy Ion Collider and $\mathrm{Pb}+\mathrm{Pb}$ collisions at the CERN Large Hadron Collider by incorporating the shadowing effects in deducing the initial energy density profile required to solve the relativistic hydrodynamical equations. We find that the thermal photon spectra remain almost unaltered; however, the elliptic flow of photons is found to be enhanced significantly due to shadowing effects.

Figure 1

Time evolutions of (a) average temperature and (b) transverse flow velocity with MCG and shMCG initial conditions have been depicted for $\nu =0$.

Figure 2

(a) Thermal photon spectra and (b) elliptic flow from MCG and shMCG initial conditions for the wounded nucleon profile at RHIC $200\mathrm{A}$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions in the 20–40% centrality bin.

Figure 3

The thermal pion spectra at the RHIC with two types of initial conditions (see text) and comparison with the PHENIX data [45].

Figure 4

Time evolutions of (a) average transverse flow velocity and (b) average temperature considering MCG and shMCG initial states for the two-component model ($\nu \ne 0$).

Figure 5

(a) Thermal photon spectra and (b) elliptic flows considering MCG and shMCG initial conditions for $200A$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions at the RHIC and 20–40% centrality bin for the two-component model.

Figure 6

(a) Thermal photon spectra and elliptic flow from (b) QGP and (c) HM separate from MCG and shMCG initial conditions.

Figure 7

Time evolutions of (a) temperature and (b) transverse velocity estimated for the LHC energy with two types of initial conditions (see text).

Figure 8

Thermal pion spectra evaluated for the LHC with two types of initial conditions (see text) and comparison with the ALICE data [46].

Figure 9

(a) The $p_T$ spectra and (b) the $v_2$ of thermal photons for the LHC energy with two types of initial conditions (see text).

Figure 10

The $v_2$ of thermal pions for the RHIC (a) and (b) LHC (b) initial conditions (see text).