NLO Productions of $\omega$ and $K_{\mathrm{S}}^0$ with a Global Extraction of the Jet Transport Parameter in Heavy Ion collisions

Abstract

In this work, we pave the way to calculate the productions of $\omega$ and $K_{\mathrm{S}}^0$ mesons at large $p_T$ in p+p and A+A collisions at the RHIC and the LHC. The $\omega$ meson fragmentation functions (FFs) in vacuum at next-to-leading order (NLO) are obtained by evolving NLO DGLAP evolution equations with rescaled $\omega$ FFs at initial scale $Q_0^2=1.5$ GeV${}^2$ from a broken SU(3) model, and the $K_{\mathrm{S}}^0$ FFs in vacuum are taken from AKK08 parametrization directly. Within the framework of the NLO pQCD improved parton model, we make good descriptions of the experimental data on $\omega$ and $K_{\mathrm{S}}^0$ in p+p both at the RHIC and the LHC. With the higher-twist approach to take into account the jet quenching effect by medium modified FFs, the nuclear modification factors for $\omega$ meson and $K_{\mathrm{S}}^0$ meson at the RHIC and the LHC are presented with different sets of jet transport coefficient ${\hat{q}}_0$. Then we make a global extraction of ${\hat{q}}_0$ at the RHIC and the LHC by confronting our model calculations with all available data on 6 identified mesons: ${\pi }^0$, $\eta$, ${\rho }^0$, $\varphi$, $\omega$, and $K_{\mathrm{S}}^0$. The minimum value of the total ${\chi }^2/d.o.f$ for productions of these mesons gives the best value of ${\hat{q}}_0=0.5\mathrm{Ge}{\mathrm{V}}^2/fm$ for Au+Au collisions with $\sqrt{s_{\mathrm{NN}}}=200$ GeV at the RHIC, and ${\hat{q}}_0=1.2\mathrm{Ge}{\mathrm{V}}^2/fm$ for Pb+Pb collisions with $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV at the LHC respectively, with the QGP spacetime evolution given by an event-by-event viscous hydrodynamics model IEBE-VISHNU. With these global extracted values of ${\hat{q}}_0$, the nuclear modification factors of ${\pi }^0$, $\eta$, ${\rho }^0$, $\varphi$, $\omega$, and $K_{\mathrm{S}}^0$ in A+A collisions are presented, and predictions of yield ratios such as $\omega /{\pi }^0$ and $K_{\mathrm{S}}^0/{\pi }^0$ at large $p_T$ in heavy-ion collisions at the RHIC and the LHC are provided.

Comments: 9 pages, 13 figures, 1 table