Neutrino Mixing and Flavour Changing Processes

TL;DR

This paper investigates how large mu-tau neutrino mixing affects flavor-changing processes in supersymmetric models with different symmetry groups and breaking patterns, highlighting constraints and predictions for rare decays.

Contribution

It provides a detailed analysis of flavor-changing transitions in supersymmetric models considering large neutrino mixing and different symmetry groups, identifying parameter restrictions and decay rate predictions.

Findings

Models with modular invariance require specific scalar and gaugino mass ratios.

Large tan beta models predict high branching ratios for mu -> e gamma.

Branching ratio BR(mu -> e gamma) exceeds 10^-14 across studied scenarios.

Abstract

We study the implications of a large nu_mu - nu_tau mixing angle on flavour changing transitions of quarks and leptons in supersymmetric extensions of the standard model. Two patterns of supersymmetry breaking are considered, models with modular invariance and the standard scenario of universal soft breaking terms at the GUT scale. The analysis is performed for two symmetry groups G x U(1)_F, with G=SU(5) and G=SU(3)^3, where U(1)_F is a family symmetry. Models with modular invariance are in agreement with observations only for restricted scalar quark and gaugino masses, (M_squark^2)/(m_gluino^2) \simeq 7/9 and m_bino > 350 GeV. A characteristic feature of models with large tan beta and radiatively induced flavour mixing is a large branching ratio for mu -> e gamma. For both symmetry groups and for the considered range of supersymmetry breaking mass parameters we find BR(mu -> e gamma) > 10^(-14).