Exotic see-saw mechanism for neutrinos and leptogenesis in a Pati-Salam model

TL;DR

This paper introduces an exotic see-saw mechanism in a Pati-Salam model derived from string theory, which predicts neutrino masses, baryon asymmetry, and neutron-antineutron oscillations, linking low-energy observables to quantum gravity effects.

Contribution

It proposes a novel exotic see-saw mechanism using stringy instantons in a D-brane Pati-Salam model, offering testable predictions for neutrino physics and baryon number violation.

Findings

Predicts a compact right-handed neutrino mass spectrum.

Provides a viable leptogenesis mechanism for baryon asymmetry.

Suggests observable neutron-antineutron oscillations.

Abstract

We discuss non-perturbative corrections to the neutrino sector, in the context of a D-brane Pati-Salam-like model, that can be obtained as a simple alternative to $SO(10)$ GUT's in theories with open and unoriented strings. In such D-brane models, exotic stringy instantons can correct the right-handed neutrino mass matrix in a calculable way, thus affecting mass hierarchies and modifying the see-saw mechanism to what we name exotic see-saw. For a wide range of parameters, a compact spectrum of right-handed neutrino masses can occur that gives rise to a predictive scenario for low energy observables. This model also provides a viable mechanism for Baryon Asymmetry in the Universe (BAU) through leptogenesis. Finally, a Majorana mass for the neutron is naturally predicted in the model, leading to potentially testable neutron-antineutron oscillations. Combined measurements in neutrino and neutron-antineutron sectors could provide precious informations on physics at the quantum gravity scale.