Search for a dark photon in e+e- collisions at BABAR

TL;DR

This paper reports a search for dark photons in electron-positron collisions using BABAR data, setting upper limits on their coupling strength and constraining parameter space related to muon magnetic moment anomalies.

Contribution

First search for dark photons in e+e- collisions at BABAR, providing new upper limits on mixing strength and narrowing the parameter space.

Findings

No significant dark photon signal observed.

Set 90% CL upper limits on mixing strength of 10^-4 to 10^-3.

Constrained dark photon parameter space related to muon g-2 anomaly.

Abstract

Dark sectors charged under a new Abelian force 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- -> gamma A', A'-> e+e-, mu+mu- using 514 fb-1 of data collected with the BABAR detector. We do not observe a significant signal 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.