Model-independent bounds on the nonoscillatory explanations of the MiniBooNE excess

We consider the nonoscillatory explanations of the low-energy excess of events detected by MiniBooNE. We present a systematic search for phenomenological scenarios based on new physics which can produce the excess. We define scenarios as series of transitions and processes which connect interactions of accelerated protons in target with single-shower events in the MiniBooNE detector. The key elements of the scenarios are production and decay of new light O(keV - 100 MeV) particles (fermions or/and bosons). We find about 20 scenarios with the minimal possible number of new particles and interaction points. In practice, they are all reduced to a few generic scenarios, and in this way we develop the effective theory of the MiniBooNE excess. We consider tests of the scenarios with near or close detectors in neutrino experiments T2K ND280, NO nu A, and MINER nu A as well as in NOMAD and PS191. The scenarios immediately connect the MiniBooNE excess and expected numbers of new physics events in these detectors. We compute the expected numbers of events as functions of the lifetimes and masses of new particles and confront them with the corresponding experimental bounds. We indicate scenarios that are excluded or strongly disfavored by one or several experiments. Given our general approach, this work can also be regarded as the effective theory of new physics at accelerator-based neutrino experiments, being relevant for future projects such as DUNE.

Automated summary

This study explores nonoscillatory explanations for the low-energy excess of events detected by MiniBooNE, searching for phenomenological scenarios based on new physics. Various scenarios are tested against experimental bounds, with excluded or strongly disfavored scenarios identified. The work can be seen as an effective theory of new physics at accelerator-based neutrino experiments, relevant for future projects like DUNE.