Suppression of Lepton Flavour Violation from Quantum Corrections above $M_{GUT}$

Abstract

We study the predictions for sfermion masses and Lepton Flavour Violation (LFV) for the WMAP preferred parameter space in $b-\tau$ Yukawa-unified models with massive neutrinos. A soft term structure as predicted by an Abelian flavour symmetry combined with SU(5) RGEs for scales above $M_{GUT}$, results to an efficient suppression of the off-diagonal terms in the scalar soft matrices, particularly for $m_0< 100$ GeV. Using the WMAP bounds, this implies $35\le\tan\beta \le 45$, $350\,\mathrm{GeV}\le m_{1/2}\le 1\,\mathrm{TeV}$, with the higher $\tan\beta$ values being favored. Within this framework, SU(5) unification becomes compatible with the current experimental bounds, in contrast to the conventional case where the soft terms are postulated at the GUT scale.