$\mu-\tau$ Reflection Symmetry in in Lepton Mixing and Radiatively Generated Leptogenesis

TL;DR

This paper explores how a specific mu-tau reflection symmetry at the GUT scale in a supersymmetric seesaw model can, through RG evolution, generate successful leptogenesis at low scales, avoiding gravitino issues.

Contribution

It introduces a scenario where mu-tau reflection symmetry leads to zero lepton asymmetry initially, but RG effects induce leptogenesis at low scales via resonant mechanisms, avoiding gravitino problems.

Findings

Resonant leptogenesis can produce the observed baryon asymmetry.

RG evolution from GUT to seesaw scale induces necessary CP violation.

Both flavor dependent and independent leptogenesis scenarios are viable.

Abstract

We study a $\mu - \tau$ reflection symmetry in neutrino sector realized at the GUT scale in the context of the seesaw model. In our scenario, the exact $\mu - \tau$ reflection symmetry realized in the basis where the charged lepton and heavy Majorana mass matrices are diagonal, leads to vanishing lepton asymmetries. We find that, in the minimal supersymmetry extension of the seesaw model with appropriate values of $\tan\beta$, the renormalization group (RG) evolution from the GUT scale to seesaw scale can induce a successful leptogenesis. It is shown that the right amount of the baryon asymmetries $\eta_B$ can be achieved via so-called resonant leptogenesis, which can be realized at rather low seesaw scale in our scenario, so that the well-known gravitino problem is safely avoided. In this work, we consider both flavor dependent and flavor independent leptogenesis, and demonstrate how they lead to different amounts of baryon asymmetries in detail.