Severe Constraints on New Physics Explanations of the MiniBooNE Excess

The MiniBooNEexperiment has recently reported an anomalous 4.5$\sigma$ excess of electron-like events consistent with $\nu_e$ appearance from a $\nu_\mu$ beam at short-baseline. Given the lack of corresponding $\nu_\mu$ disappearance observations, required in the case of oscillations involving a sterile flavor, there is strong motivation for alternative explanations of this anomaly. We consider the possibility that the observed electron-like signal may actually be due to hypothetical new particles,which do not involve new sources of neutrino production or oscillations. We find that the electron-like event energy and angular distributions in the full MiniBooNEdata-set, including neutrino mode, antineutrino mode, and beam dumpmode, severely limit, and in some cases rule out, new physics scenarios as an explanation for the observed neutrino and antineutrino mode excesses. Specifically, scenarios in which the new particle decays(visibly or semi-visibly) or scatters elastically in the detector are strongly disfavored. Using generic kinematic arguments, this paper extends the existing MiniBooNEresults and interpretations to exhaustively constrain previously unconsidered new physics signatures and emphasizes the power of the MiniBooNE beam dumpsearch to further constrain models for the excess.