Lepton flavor violation and seesaw symmetries

TL;DR

This paper explores how a slightly broken U(1)R symmetry in minimal seesaw models influences charged lepton flavor violation, showing that decay rates can be within measurable ranges and are determined by neutrino data.

Contribution

It demonstrates that U(1)R symmetry breaking can lead to observable lepton flavor violating decays, linking them directly to neutrino data in minimal seesaw models.

Findings

Charged lepton flavor violating rates can be within measurable ranges.

Decay rates are determined by neutrino data up to a normalization factor.

Lepton flavor violation can be sizable across a wide right-handed neutrino mass range.

Abstract

When the standard model is extended with right-handed neutrinos the symmetries of the resulting Lagrangian are enlarged with a new global U(1)R Abelian factor. In the context of minimal seesaw models we analyze the implications of a slightly broken U(1)R symmetry on charged lepton flavor violating decays. We find, depending on the R-charge assignments, models where charged lepton flavor violating rates can be within measurable ranges. In particular, we show that in the resulting models due to the structure of the light neutrino mass matrix muon flavor violating decays are entirely determined by neutrino data (up to a normalization factor) and can be sizable in a wide right-handed neutrino mass range.