Yorito Yamaguchi (University of Tokyo)
A dark photon is a hypothetical particle which is very weakly coupled with ordinary photons in some Beyond the Standard Model (BSM) theories. The dark photon is a candidate for the annihilation of dark matter particles into $e^+e^-$ pairs, a process which could provide an explanation for the positron excess in the universe observed by several satellite experiments. It may also explain the $3\sigma$ discrepancy between the muon $g-2$ result and Standard Model calculations. The PHENIX experiment at RHIC has excellent capabilities for electron identification and for measuring $e^+e^-$ pairs with a very good mass resolution, making possible a search for such pairs from dark photon decay. We have conducted a search for possible $e^+e^-$ pairs from dark photons among a large data sample of pairs from $\pi^0$ Dalitz decays. We present new results of the dark photon search from the PHENIX experiment, which provide the world's best limits and rules out a majority of the mass-branching ratio region that could explain the $g-2$ result.
|On behalf of collaboration:||PHENIX|
Dr Dave Morrison (Brookhaven National Laboratory)