LFV radiative Decays and Leptogenesis in the SUSY seesaw model

TL;DR

This paper investigates lepton flavor violation and leptogenesis within the SUSY seesaw model, revealing that natural parameter choices predict decay rates exceeding experimental limits unless specific neutrino Yukawa structures are assumed.

Contribution

It introduces a detailed analysis of LFV decays and leptogenesis in the SUSY seesaw framework, highlighting the impact of neutrino Yukawa structures on observable predictions.

Findings

Predicted mu to e + gamma decay rate exceeds experimental bounds for natural parameters.

Successful leptogenesis imposes a lower bound on the lightest heavy Majorana neutrino mass.

Certain neutrino Yukawa coupling structures can reconcile predictions with experimental limits.

Abstract

The lepton flavour violating charged lepton decays mu to e + gamma and thermal leptogenesis are analysed in the minimal supersymmetric standard model with see-saw mechanism of neutrino mass generation and soft supersymmetry breaking terms with universal boundary conditions. Hierarchical spectrum of heavy Majorana neutrino masses, M_1 << M_2 << M_3, is considered. In this scenario, the requirement of successful thermal leptogenesis implies a lower bound on M_1. For the natural GUT values of the heaviest right-handed Majorana neutrino mass, M_3 > 5 times 10^{13} GeV, and supersymmetry particle masses in the few times 100 GeV range, the predicted mu to e + gamma decay rate exceeds by few order of magnitude the experimental upper limit. This problem is avoided if the matrix of neutrino Yukawa couplings has a specific structure. The latter leads to a correlation between the baryon asymmetry of the Universe predicted by leptogenesis, BR(mu to e + gamma) and the effective Majorana mass in neutrinoless double beta decay.