Proton Stability and Dark Matter in a Realistic String MSSM

TL;DR

This paper presents a string theory model with an extra gauge symmetry that prevents proton decay and offers potential dark matter candidates, with implications for collider and direct detection experiments.

Contribution

It introduces a realistic string-derived Pati-Salam model featuring a nonanomalous U(1) symmetry that forbids proton decay operators and explores dark matter detection prospects.

Findings

Extra U(1) symmetry forbids proton decay mediating operators.

Model predicts potential leptophobic and leptophilic Z' bosons at LHC.

Dark matter direct detection cross-sections are within experimental reach.

Abstract

We demonstrate the existence of an extra nonanomalous U(1) gauge symmetry in a three-generation Pati-Salam model constructed with intersecting D6-branes in Type IIA string theory on a T^6/(Z_2 \times Z_2) orientifold. This extra U(1) forbids all dimension-4, 5, and 6 operators which mediate proton decay in the MSSM. Moreover, this results in the effective promotion of baryon and lepton number to local gauge symmetries, which can potentially result in leptophobic and leptophilic $Z'$ bosons observable at the LHC. Furthermore, it is not necessary to invoke R-parity to forbid the dimension-4 operators which allow rapid proton decay. However, R-parity may arise naturally from a spontaneously broken U(1)_{B-L}. Assuming the presence of R-parity, we then study the direct detection cross-sections for neutralino dark matter, including the latest constraints from the XENON100 experiment. We find that these limits are now within required range necessary to begin testing the model.