Superstring-inspired models

Abstract

We discuss the structure of low-energy groups arising from compactified models based on the heterotic string. Particular regard is paid to the possibility of intermediate scale breaking which may change the low-energy gauge structure and may naturally lead to doublet-triplet splitting and the suppression of proton decay. We present an illustrative example of such a model with a low energy gauge group structure SU 3 c × SU 2 L × SU 2 R × U 1 B−L which may be compatible with low-energy phenomena including limits on neutrino masses and sin 2 θ W. Mechanisms leading to the minimal SU 3 c × SU 2 L × U 1 Y low-energy gauge group are also presented.