Centrality dependence of p_T spectra for identified hadrons in Au+Au and Cu+Cu collisions at √s_NN = 200 GeV^*

The centrality dependence of transverse momentum spectra for identified hadrons at midrapidity in Au+Au collisions at √s_NN = 200GeV is systematically studied in a quark combination model. The p_T spectra of π^±, K^±, p() and Λ() 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 ⟨β(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 p_T spectra and the R_CP for π⁰, K_s⁰ and Λ in Cu+Cu collisions at √s_NN = 200 GeV are well described. The results show that ⟨β(r)⟩ is only a function of the number of participants N_part and it is independent of the collision system.