U (1) ′ mediated decays of heavy sterile neutrinos in MiniBooNE

Abstract

The MiniBooNE low-energy excess is a long-standing problem which has received further confirmation with a reanalysis using newly collected data, with the anomaly now at the 4.8σ level. In this paper we propose a novel explanation which advocates a low-energy sector containing Z′ bosons with GeV-scale masses and sterile neutrinos with masses around 100-500 MeV. We show that this scenario provides excellent spectral agreement with the MiniBooNE low-energy excess in the form of Z′-mediated neutral current production of heavy sterile states, a fraction of whose subsequent decay to e+e- pairs are misidentified as single electronlike electromagnetic showers. Our model inscribes itself in the broad class of models in which sterile neutrinos are charged under new interactions, allowing new couplings to hidden-sector physics. Alongside the electronlike MiniBooNE signature this model also predicts a novel, low-background, signal in LArTPC detectors such as MicroBooNE consisting of two distinguishable electronlike electromagnetic showers originating from a single vertex.