Lepton flavour violation from right-handed neutrino thresholds

Abstract

Charged lepton flavour violation is reappraised in the context of supersymmetric see-saw mechanism. It is pointed out that a non-trivial flavour structure of right-handed neutrinos, whose effect has been thus far less studied, can give rise to significant slepton flavour transitions. Under the premise that the neutrino Yukawa couplings are of O(1), the right-handed neutrino mixing contribution could form a basis of the $\mu \to e\gamma$ amplitude which by itself might lead to an experimentally accessible rate, given a typical low-energy sparticle spectrum. Emphasis is placed on the crucial role of the recently measured lepton mixing angle ${\theta }_{13}$ as well as the leptonic CP-violating phases.

Comments: 6 pages, changed title, added spurion interpretation, conclusions unchanged, published version