Searches for low mass CP-odd Higgs and dark photons at BaBar

Abstract

We report recent searches for new physics by the BaBar experiment in two sectors: the search for dark photons and the search for CP-odd light Higgs A0. We do not observe significant signals. 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/c2. We further constrain the range of the dark photon parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon. We set 90% confidence-level upper limits on the product branching fraction B(ϒ(1S)→γA0)⋅B(A0→gg or ss¯) ranging from 10−6 to 10−2 for A0 masses in the range 0.5 to 9.0 GeV/c2.