Toshihiko Ota

Lepton flavor violation in Higgs boson decays under the rare tau decay results

We study lepton flavor violation (LFV) associated with tau leptons in the framework of the two Higgs doublet model, in which LFV couplings are introduced as a deviation from Model II Yukawa interaction. Parameters of the model are constrained from experimental results and also from requirements of theoretical consistencies such as vacuum stability and perturbative unitarity. Current data for rare tau decays provide substantial upper limits on the LFV Yukawa couplings in the large tan{beta} region (tan{beta} > or approx. 30), which are comparable with predictions in fundamental theories. Here tan{beta} is the ratio of vacuum expectation values of the two Higgs doublets. We show that a search for the LFV decays {phi}{sup 0}{yields}{tau}{sup {+-}}{mu}{sup {+-}} ({tau}{sup {+-}}e{sup {+-}}) of neutral Higgs bosons ({phi}{sup 0}=h,H and A) at future collider experiments can be useful to further constrain the LFV couplings especially in the relatively small tan{beta} region (tan{beta} < or approx. 30), where rare tau decay data cannot give any strong limit.

Oscillation-enhanced search for new interaction with neutrinos

We discuss the measurement of new physics in long baseline neutrino oscillation experiments. Through neutrino oscillations, the probability to detect new physics effects such as flavor violation is enhanced by interference with the weak interaction. We carefully explain the situations in which interference can take place. Assuming a neutrino factory and an upgraded conventional beam, we estimate the feasibility to observe new physics numerically and point out that we can search new interactions using some channels, for example,

Search for lepton flavor violation in the Higgs boson decay at a linear collider

{ensuremath{nu}}_{ensuremath{mu}}ensuremath{rightarrow}{ensuremath{nu}}_{ensuremath{mu}},

Can ICARUS and OPERA ντ appearance experiments detect new flavor physics

in these experiments. We also discuss several models which induce effective interactions interfering with the weak interaction, and show that some new physics effects are large enough to be observed in an oscillation enhanced way.

A study of lepton flavor violating μN(eN) → τX reactions in supersymmetric models

We study possibility of observing the process

Yet another correlation in the analysis of CP violation using a neutrino oscillation experiment

h^{0} to tau^{pm} mu^{mp}

Search for T-violation in neutrino oscillation with the use of muon polarization at a neutrino factory

at a linear collider. The branching ratio is constrained to be of the order of

Signature of the minimal supersymmetric standard model with right-handed neutrinos in long baseline experiments

10^{-4}

Enhancement of lepton flavor violation in a model with bimaximal mixing at the grand unification scale

by the

Matter profile effect in a neutrino factory: yet another correlation in the analysis on CP violation at a neutrino oscillation experiment

tau^{-} to mu^{-} eta