Centrality dependence of $p_T$ spectra for identified hadrons in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV

Abstract

The centrality dependence of transverse momentum spectra for identified hadrons at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV is systematically studied in a quark combination model. The ${\mathrm{p}}_{\mathrm{T}}$ spectra of $\ddot{I}{€}^{\pm }$, $K^{\pm }$, $p(\bar{p})$ and $\hat{I}›(\bar{\hat{I}}›)$ in different centrality bins and the nuclear modification factors ($R_{CP}$) for these hadrons are calculated. The centrality dependence of the average collective transverse velocity $<{\hat{I}}^2(r)>$ for the hot and dense quark matter is obtained in Au+Au collisions, and it is applied to a relative smaller Cu+Cu collision system. The centrality dependence of ${\mathrm{p}}_{\mathrm{T}}$ spectra and the $R_{CP}$ for $\ddot{I}{€}^0$, $K_s^0$ and $\hat{I}›$ in Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV are well described. The results show that $<{\hat{I}}^2(r)>$ is only a function of the number of participants $N_{part}$ and it is independent of the collision system.

7 pages, 6 figures