Elliptic flow of identified particles at 62 and 200 GeV: similarities and differences

摘要

1. To first order also identified particle v_2(p_t) and v_4(p_t) are very similar at 62 and 200 GeV 1.1 Typical mass dependence observed at low-p_t at both energies, mass scaling broken at intermediate p_t where baryon meson scaling is observed for both energies 2. Pions have a different non-flow contribution than protons at intermediate p_t 3. The small differences observed between v_2(p_t) for pions at 62 and 200 GeV are consistent with small increase in radial flow and an increase in its azimuthal dependence 3.1 Need model calculations to see if this is consistent with hydrodynamics or LDL 4. The centrality dependence is slightly shifted between 62 and 200 GeV 4.1 The 200 GeV pion v_2 peaks at more peripheral collisions 5. v_4 scales with V_(2~2) as function of p_t and the ratio is about unity for both energies Disclaimer: the data are still preliminary and because the differences are small mere systematic checks are being performed.