Light sterile neutrinos, lepton number violating interactions, and the LSND neutrino anomaly

摘要

We develop the consequences of introducing a purely leptonic, lepton number violating nonstandard interaction (NSI) and standard model neutrino mixing with a fourth, sterile neutrino in the analysis of short baseline, neutrino experiments. We focus on the muon decay at rest (DAR) results from the Liquid Scintillation Neutrino Experiment (LSND) and the Karlsruhe and Rutherford Medium Energy Neutrino Experiment. We make a comprehensive analysis of lepton number violating, NSI effective operators and find nine that affect muon decay relevant to LSND results. Two of these preserve the standard model value 3/4 for the Michel rho and delta parameters and, overall, show favorable agreement with precision data and the (nu) over bar (e) signal from LSND data. We display theoretical models that lead to these two effective operators. In the model we choose to apply to DAR data, both (nu) over bar (e) appearance from (nu) over bar (mu) oscillation and (nu) over bar (e) survival after production from NSI decay of the mu(+) contribute to the expected signal. This is a unique feature of our scheme. We find a range of parameters where both experiments can be accommodated consistently with recent global, sterile neutrino fits to short baseline data. We comment on implications of the models for new physics searches at colliders and comment on further implications of the lepton number violating interactions plus sterile neutrino-standard neutrino mixing.