Large mixing angle MSW and atmospheric neutrinos from single right-handed neutrino dominance and U(1) family symmetry

Abstract

Single right-handed neutrino dominance (SRHND) in the 23 sector of the light\neffective neutrino mass matrix has been proposed as a natural explanation for\nthe concurrent large 23 mixing angle and large 23 mass hierarchy. In this paper\nwe show how large 12 mixing angles, suitable for the large mixing angle (LMA)\nMSW solution to the solar neutrino problem, may arise from SRHND. In order to\nunderstand the conditions for SRHND and LMA MSW we first consider the case of\none and two right-handed neutrinos, and obtain simple analytic conditions which\nare then extended to the case of three right-handed neutrinos. We then\nintroduce a single U(1) family symmetry and show how these analytic conditions\nmay be translated into U(1) charge assignments and perform a systematic search\nfor the simplest examples.\n