Search

We present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (|y| < 0.35) in Au + Au collisions at √SNN= 62.4 GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range 1 < pTe < 5 GeV/c. The invariant yield per binary collision is slightly enhanced above the p + p reference in Au + Au 0%-20%, 20%-40%, and 40%-60% centralities at a comparable level. At this low beam energy this may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss in medium. The v2 of electrons from heavy-flavor decays is nonzero when averaged between 1.3 < pTe < 2.5 GeV/c for 0%-40% centrality collisions at √SNN= 62.4 GeV For 20%-40% centrality collisions, the v2 at √SNN= 62.4 GeV is smaller than that for heavy-flavor decays at √SNN= 62.4 GeV. The v2 of the electrons from heavy-flavor decay at the lower beam energy is also smaller than v2 for pions. Both results indicate that the heavy quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed √SNN= 200 GeV. [ABSTRACT FROM AUTHOR]

We report on J/ψ production from asymmetric Cu + Au heavy-ion collisions at √SNN = 200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/ψ yields in Cu + Au collisions in the Au-going direction is found to be comparable to that in Au + Au collisions when plotted as a function of the number of participating nucléons. In the Cu-going direction, J/ψ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger IOW-JC gluon suppression in the larger Au nucleus. [ABSTRACT FROM AUTHOR]