Z_2 orbifold compactification of heterotic string and 6D SO(16) and E_7 times SU(2) flavor unification models

TL;DR

This paper explores Z_2 orbifold compactification of heterotic string theory, resulting in 6D GUT models with SO(16) or E_7×SU(2), reducing supersymmetry and connecting to lower-dimensional unification models.

Contribution

It introduces specific 6D GUT models from heterotic string orbifold compactification, detailing the reduction of supersymmetry and the connection to previous 5D unification models.

Findings

6D GUT models with SO(16) or E_7×SU(2) derived from heterotic string

Reduction of N=4 to N=2 supersymmetry in compactification

Connection to 5D SO(16) and SO(14) family unification models

Abstract

A Z_2 orbifold compactification of the heterotic string is considered. The resulting 6D GUT groups can be SO(16) or E_7 times SU(2) plus some hidden sector groups. The N=4 supersymmetry is reduced to N=2. In particular, the SO(16) 6D model with one spinor representation 128 can reduce to the previous 5D SO(16) or SO(14) family unification models after compactifying the sixth dimension. To obtain one spinor, we have to take into account the left-over center of SO(16). We also comment on the E_7 times SU(2) model.