Lepton flavor violation in the supersymmetric seesaw model after the LHC 8 TeV run

Abstract

We study the lepton flavor violation in the supersymmetric seesaw model, taking into account recent experimental improvements, especially for the Higgs boson mass measurement, direct searches of superpartners, and the rare decay of ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ at the LHC; the neutrino mixing angle of ${\ensuremath{\theta}}_{13}$ in the neutrino experiments; and the search of $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$ in the MEG experiment. We obtain the latest constraints on the parameters in the supersymmetry-breaking terms and study the effect on the lepton-flavor-violating decays of $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$ and $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$. In particular, we consider two kinds of assumption on the structures in the Majorana mass matrix and the neutrino Yukawa matrix. In the case of the Majorana mass matrix proportional to the unit matrix, allowing nonvanishing $CP$-violating parameters in the neutrino Yukawa matrix, we find that the branching ratio of $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$ can be larger than ${10}^{\ensuremath{-}9}$ within the improved experimental limit of $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$. We also consider the neutrino Yukawa matrix that includes the mixing only in the second and third generations, and we find that a larger branching ratio of $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$ than ${10}^{\ensuremath{-}9}$ is possible while satisfying the recent constraints.