Lepton flavor violation as a probe of quark-lepton unification

Abstract

The recent measurements of the solar neutrino mixing angle ${\ensuremath{\theta}}_{\mathrm{sol}}$ and the Cabibbo mixing angle ${\ensuremath{\theta}}_{C}$ reveal a surprising relation, ${\ensuremath{\theta}}_{\mathrm{sol}}+{\ensuremath{\theta}}_{C}\ensuremath{\simeq}\frac{\ensuremath{\pi}}{4}$, which has been interpreted as an evidence for quark-lepton unification. We show in realizations of quark-lepton unification that the PMNS mixing matrix can be decomposed into a CKM-like matrix and maximal mixing matrices. We explore a possibility to probe such implications by considering the relative sizes of branching ratios for the lepton flavor violating radiative decay processes, ${l}_{i}\ensuremath{\rightarrow}{l}_{j}\ensuremath{\gamma}$, in the context of the supersymmetric standard model with heavy right-handed Majorana neutrinos.