Production of $ρ^{0}$ meson with large $p_T$ at NLO in heavy-ion collisions
Production of large transverse momentum $ρ^{0}$ meson in high-energy nuclear collisions is investigated for the first time at the next-leading-order in the QCD improved parton model. The $ρ^0$ fragmentation functions (FFs) in vacuum at any scale $Q$ are obtained, by evolving a newly developed initial parametrization of $ρ^0$ FFs at a scale $\rm Q_{0}^2=1.5\ GeV^2$ from a broken SU(3) model through NLO DGLAP equations. The numerical simulations of $p_{\rm T}$ spectra of $ρ^{0}$ meson in the elementary $\rm p+p$ collisions at NLO give a decent description of STAR $\rm p+p$ data. In $\rm A+A$ 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 $ρ^{0}$ meson and its double ratio with $π^\pm$ nuclear modification in central $\rm Au+Au$ collisions at the RHIC are calculated and found to be in good agreement with STAR measurement. Predictions of $ρ^{0}$ nuclear modification and the yield ratio $ρ^0/π^0$ in central Pb+Pb at the LHC are also presented. It is shown that the ratio $ρ^0/π^0$ in central Pb+Pb will approach to that in p+p reactions when $p_{\rm T}>12$~GeV.