Way-out to the Gravitino problem in intersecting D-brane Pati-Salam models

TL;DR

This paper explores how in intersecting D-brane Pati-Salam models, gravitinos as super heavy dark matter particles can resolve the gravitino problem, linking neutrino physics, dark matter, and string compactifications.

Contribution

It proposes a scenario where gravitinos as stable, super heavy dark matter resolve the gravitino problem in high-scale SUSY models within D-brane constructions.

Findings

Gravitinos can be the Lightest Stable SUSY Particles avoiding decay issues.

Bounds on dark matter abundance constrain neutrino sector and string compactifications.

High-energy neutrino and photon detection could observe gravitino decay signatures.

Abstract

We discuss the gravitino problem in contest of the Exotic see-saw mechanism for neutrinos and Leptogenesis, UV completed by intersecting D-branes Pati-Salam models. In the Exotic see-saw model, supersymmetry is broken at high scales $M_{SUSY}>10^{9}\, \rm GeV$ and this seems in contradiction with gravitino bounds from inflation and baryogenesis. However, if gravitino is the Lightest Stable Supersymmetric Particle, it will not decay into other SUSY particles, avoiding the gravitino problem and providing a good Cold Dark Matter. Gravitini are Super Heavy Dark Particles and they can be produced by non-adiabatic expansion during inflation. Intriguingly, from bounds on the correct abundance of dark matter, we also constrain the neutrino sector. We set a limit on the exotic instantonic coupling of $<10^{-2}\div 10^{-3}$. This also sets important constrains on the Calabi-Yau compactifications and on the string scale. This model strongly motivates very high energy DM indirect detection of neutrini and photons of $10^{11}\div 10^{13}\, \rm GeV$: gravitini can decay on them in a cosmological time because of soft R-parity breaking effective operators.