Production of ${\rho }^0$ meson with large $p_T$ at NLO in heavy-ion collisions

Abstract

Production of large transverse momentum ${\rho }^0$ meson in high-energy nuclear collisions is investigated for the first time at the next-leading-order in the QCD improved parton model. The ${\rho }^0$ fragmentation functions (FFs) in vacuum at any scale $Q$ are obtained, by evolving a newly developed initial parametrization of ${\rho }^0$ FFs at a scale ${\mathrm{Q}}_0^2=1.5\mathrm{Ge}{\mathrm{V}}^2$ from a broken SU(3) model through NLO DGLAP equations. The numerical simulations of $p_{\mathrm{T}}$ spectra of ${\rho }^0$ meson in the elementary $\mathrm{p}+\mathrm{p}$ collisions at NLO give a decent description of STAR $\mathrm{p}+\mathrm{p}$ data. In $\mathrm{A}+\mathrm{A}$ reactions the jet quenching effect is taken into account with the higher-twist approach by the medium-modified parton FFs due to gluon radiation in the quark-gluon plasma, whose space-time evolution is described by a (3+1D) hydrodynamical model. The nuclear modification factors for ${\rho }^0$ meson and its double ratio with ${\pi }^{\pm }$ nuclear modification in central $\mathrm{Au}+\mathrm{Au}$ collisions at the RHIC are calculated and found to be in good agreement with STAR measurement. Predictions of ${\rho }^0$ nuclear modification and the yield ratio ${\rho }^0/{\pi }^0$ in central Pb+Pb at the LHC are also presented. It is shown that the ratio ${\rho }^0/{\pi }^0$ in central Pb+Pb will approach to that in p+p reactions when $p_{\mathrm{T}}>12$~GeV.

Comments: 6 pages, 6 figures. Final version accepted for publication in PRC