Transverse momentum dependence of charged and strange hadron elliptic flows in Cu?Cu collisions

We investigate the dependence of elliptic flows v2 on transverse momentum PT for charged and strange hadrons produced in Cu?Cu collisions by using a multi-source thermal model, which includes the interaction contribution of the emission sources. The magnitude of the expansion is denoted by a expansion factor k. Our calculated results are approximately in agreement with the experimental data in Cu?Cu collisions at = 62.4 and 200 GeV, measured by the STAR Collaboration. It is found that the expansion factor increases linearly with the impact parameter from the most central (0?10%) to mid-peripheral (40?50%) collisions.