Published by Institute of Physics Publishing for SISSA Received: May 31, 2005 Revised: August 22, 2005 Accepted: September 8, 2005 Published: September 19, 2005 Explaining LSND by a decaying sterile neutrino Sergio Palomares-Ruiz Department of Physics and Astronomy, Vanderbilt University JHEP09(2005)048 Nashville, TN 37235, U.S.A. E-mail:
[email protected] Silvia Pascoli Physics Department, Theory Division, CERN CH–1211 Geneva 23, Switzerland E-mail:
[email protected] Thomas Schwetz Scuola Internazionale Superiore di Studi Avanzati Via Beirut 2–4, I–34014 Trieste, Italy E-mail:
[email protected] Abstract: We propose an explanation of the LSND evidence for electron antineutrino appearance based on neutrino decay. We introduce a heavy neutrino, which is produced in pion and muon decays because of a small mixing with muon neutrinos, and then decays into a scalar particle and a light neutrino, predominantly of the electron type. We require values of gm few eV, g being the neutrino-scalar coupling and m the heavy neutrino 4 ∼ 4 mass, e.g. m in the range from 1 keV to 1 MeV and g 10−6–10−3. Performing a fit 4 ∼ to the LSND data as well as all relevant null-result experiments, we show that all data can be explained within this decay scenario. In the minimal version of the decay model, we predict a signal in the upcoming MiniBooNE experiment corresponding to a transition probability of the same order as seen in LSND. In addition, we show that extending our model to two nearly degenerate heavy neutrinos it is possible to introduce CP violation in the decay, which can lead to a suppression of the signal in MiniBooNE running in the neutrino mode.