paper

Lepton flavor violating tau and B decays and heavy neutrinos

arXiv:hep-ph/0409346 · doi:10.1103/PhysRevD.70.113011

Abstract

We study lepton flavor violating (LFV) tau and B decays in models with heavy neutrinos to constrain the mixing matrix parameters U_{tau N}. We find that the best current constraints when the heavy neutrinos are purely left-handed come from LFV radiative tau decay modes. To obtain competitive constraints in LFV B decay it is necessary to probe b -> X_{s} tau^{\pm} e^{\mp} at the 10^{-7} level. When the heavy neutrinos have both left and right-handed couplings, the mixing parameters can be constrained by studying LFV B decay modes and LFV tau decay into three charged leptons. We find that the branching ratios B(tau^{\pm} -> l_1^{\pm} l_2^{\pm} l_3^{\mp}), B(B_{s} -> tau^{\pm} e^{\mp}) and B(b -> X_{s} l_1^{\pm} l_2^{\mp}) need to be probed at the 10^{-8} level in order to constrain the mixing parameters beyond what is known from unitarity.

arXiv comment24 pages,8 figures. Discussion and comparison with the literature added. CLEO results updated. Conclusions unchanged

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