R-parity from string compactification

TL;DR

This paper presents a method to derive R-parity from string theory compactification, specifically using anti-SU(5) GUT models within heterotic string frameworks, to address particle family structure and symmetry breaking.

Contribution

It introduces a novel approach to assign Z4R parity in string compactifications with specific GUT models and hidden sectors, reducing the number of representations compared to MSSMs.

Findings

Successful assignment of Z4R parity in string models.

Construction of an anti-SU(5) GUT with three families.

Symmetry breaking achieved via specific Higgs fields.

Abstract

The strategy for assigning $Z_{4R}$ parity in the string compactification is presented. For the visible sector, an anti-SU(5) (flipped-SU(5)) grand unification (GUT) model with three families is used to reduce the number of representations compared to the number in the minimal supersymmetric standard models (MSSMs). The SO(32) heterotic string is used to allow a large nonabelian gauge group SU($N$), $N\ge 9$, for the hidden sector such that the number of extra U(1) factors is small. A discrete subgroup of the gauge U(1)'s is defined as the $Z_{4R}$ parity. Spontaneous symmetry breaking of anti-SU(5) GUT is achieved by the vacuum expectation values of two index antisymmetric tensor Higgs fields ${\bf 10}_{+1}$ and $\overline{\bf 10}_{-1}$ that led to our word `anti-SU(5)'. In the illustrated example, the multiplicity 3 in one twisted sector allows the permutation symmetry $S_3$ that leads us to select the third family members and one MSSM pair of the Higgs quintets.