A non-QE signature of nu_e appearance in a water Cherenkov detector

Abstract

We argue that analyzing the nu_e- and bar{nu_e}-induced CC reactions nu_e n --> e^- pi^0 p and bar{nu}_e p --> e^+ pi^0 n along with quasielastics may significantly enhance the sensitivity of a water Cherenkov detector to subleading oscillations nu_mu --> nu_e and bar{nu}_mu --> bar{nu}_e at neutrino energies ~ 2 GeV, as projected for the off-axis neutrino beam of NuMI.The neutral-current background to these reactions is less than to quasielastics, and can be further suppressed by reconstructing theprimary vertex of the collision.