meson production in the forward/backward rapidity region in Cu + Au collisions at = 200 GeV

Adare, A.*; Hasegawa, Shoichi   ; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 505 of others*

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured meson production and its nuclear modification in asymmetric Cu + Au heavy-ion collisions at = 200 GeV at both forward Cu-going direction (1.2 y 2.2) backward Au-going direction (-2.2 y -1.2) rapidities. The measurements are performed via the dimuon decay channel and reported as a function of the number of participating nucleons, rapidity, and transverse momentum. In the most central events, 0% - 20% centrality, the meson yield integrated over 1 5 GeV/ prefers a smaller value, which means a larger nuclear modification, in the Cu-going direction compared to the Au-going direction. Additionally, the nuclear-modification factor in Cu + Au collisions averaged over all centrality is measured to be similar to the previous PHENIX result in + Au collisions for these rapidities.