Light Sterile Neutrinos, Lepton Number Violating Interactions and the LSND Anomaly

Understand

We develop the consequences of introducing a purely leptonic, lepton number violating non-standard 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) result from the Liquid Scintillation Neutrino Experiment (LSND) and the Karlsruhe and Rutherford Medium Energy Neutrino Experiment (KARMEN).
• 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 (SM) value 3/4 for the Michel rho and delta parameters and, overall, show favorable agreement with precision data and the electron anti-neutrino signal from LSND data.