meson production in + Au collisions at = 200 GeV

Adare, A.*; Hasegawa, Shoichi   ; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 477 of others*

The PHENIX Collaboration has measured meson production in + Au collisions at = 200 GeV using the dimuon and dielectron decay channels. The meson is measured in the forward (backward) -going (Au-going) direction, in the transverse-momentum () range from 1-7 GeV/ and at midrapidity in the range below 7 GeV/. The meson invariant yields and nuclear-modification factors as a function of , rapidity, and centrality are reported. An enhancement of meson production is observed in the Au-going direction, while suppression is seen in the -going direction, and no modification is observed at midrapidity relative to the yield in collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.