Search for dark photons from neutral meson decays in and +Au collisions at GeV

Adare, A.*; Hasegawa, Shoichi   ; Imai, Kenichi; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 574 of others*

The standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment deviates from SM calculations by . Several theoretical models attribute this to the existence of a "dark photon", an additional gauge boson, which is weakly coupled to ordinary photons. The PHENIX experiment at the Relativistic Heavy Ion Collider has searched for a dark photon, , in decays and obtained upper limits of O(2 on - mixing at 90% C.L. for the mass range . Combined with other experimental limits, the remaining region in the - mixing parameter space that can explain the deviation from its SM value is nearly completely excluded at the 90% confidence level, with only a small region of remaining.