Search for a Dark Photon in e^{+}e^{-} Collisions at BaBar.

Lees JP , Poireau V , Tisserand V , Grauges E , Palano A , Eigen G , Stugu B , Brown DN , Feng M , Kerth LT , Kolomensky YG , Lee MJ , Lynch G , Koch H , Schroeder T , Hearty C , Mattison TS , McKenna JA , So RY , Khan A , Blinov VE , Buzykaev AR , Druzhi
Physical review letters
Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514  fb^{-1} of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^{-4}-10^{-3} for dark photon masses in the range 0.02-10.2  GeV. We further constrain the range of the parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon.

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