Abstract
The PHENIX experiment at the Relativistic Heavy Ion Collider has performed systematic measurements of meson production in the decay channel at midrapidity in , , , and collisions at . Results are presented on the invariant yield and the nuclear modification factor for and , and for collisions, studied as a function of transverse momentum () and centrality. In central and midcentral collisions, the of exhibits a suppression relative to expectations from binary scaled results. The amount of suppression is smaller than that of the and the in the intermediate range (), whereas, at higher , the , , and show similar suppression. The baryon (proton and antiproton) excess observed in central collisions at intermediate is not observed for the meson despite the similar masses of the proton and the . This suggests that the excess is linked to the number of valence quarks in the hadron rather than its mass. The difference gradually disappears with decreasing centrality, and, for peripheral collisions, the values for both particle species are consistent with binary scaling. collisions show the same yield and suppression as collisions for the same number of . The of shows no evidence for cold nuclear effects within uncertainties.
- Received 20 April 2010
DOI:https://doi.org/10.1103/PhysRevC.83.024909
©2011 American Physical Society