Status of neutrino oscillations II: How to reconcile the LSND result?

Abstract

We present an analysis of the global neutrino oscillation data including the LSND result in terms of four-neutrino mass schemes and a CPT violating three-neutrino framework. We find that the strong preference of oscillations into active neutrinos implied by recent solar+KamLAND as well as atmospheric neutrino data allows to rule out (2+2) mass schemes at 5.8\(\sigma\), whereas (3+1) schemes are disfavoured at the 3.2\(\sigma\) level by short-baseline experiments. The CPT violating scenario is disfavoured at 3.4\(\sigma\) by KamLAND and atmospheric anti-neutrino data. We conclude that currently no convincing explanation for the LSND signal exists, and it remains a puzzle how to reconcile it with the other evidences for neutrino oscillations.