On Discrete R-Symmetries in MSSM and its Extensions

TL;DR

This paper explores anomaly-free discrete R-symmetries in the MSSM and its extensions, focusing on charge assignments that commute with flipped-SU(5) and addressing the ta-problem and dangerous operators.

Contribution

It identifies specific Z_N symmetries compatible with flipped-SU(5) that solve key issues in MSSM extensions, including anomaly cancellation mechanisms.

Findings

Z_N symmetries with N=3,6 (anomaly-free) and N=3,4,6,8,12,24 (Green-Schwarz) are found.

Constructed a 4D flipped-SU(5) GUT model with phenomenologically acceptable Z_N symmetries.

Discussed non-unified cases like Z_5 in the context of anomaly considerations.

Abstract

We study possible anomaly-free discrete R-symmetries that avoid the \mu-problem and the dangerous D\leq 5 operators considering charge assignments that do not commute with the traditional grand unifying simple groups, such as SU(5) or SO(10), but commute instead with the so-called flipped-SU(5), with or without the operation of the GS mechanism. We find Z_N symmetries with N = 3, 6 in the anomaly-free case or N = 3, 4, 6, 8, 12, 24 in the case of anomaly cancellation through the Green-Schwartz mechanism. Non-unified cases (Z_5) have also been discussed. We also confront the construction of a 4D grand unified flipped-SU(5) model endowed with Z_N and find phenomenologically acceptable solutions with N = 2k+7 and N = 2k+10.