Measurement of the relative yields of to mesons produced at forward and backward rapidity in , Al, Au, and He+Au collisions at GeV

Adare, A.*; Hasegawa, Shoichi   ; Imai, Kenichi; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 361 of others*

The PHENIX Collaboration has measured the ratio of the yields of to mesons produced in , Al, Au, and He+Au collisions at GeV over the forward and backward rapidity intervals . We find that the ratio in collisions is consistent with measurements at other collision energies. In collisions with nuclei, we find that in the forward (-going or He-going) direction, the relative yield of mesons to mesons is consistent with the value measured in collisions. However, in the backward (nucleus-going) direction, the meson is preferentially suppressed by a factor of . This suppression is attributed in some models to the breakup of the weakly bound meson through final-state interactions with comoving particles, which have a higher density in the nucleus-going direction. These breakup effects may compete with color screening in a deconfined quark-gluon plasma to produce sequential suppression of excited quarkonia states.