Gauge symmetry reduction from the extra space S1/z2

Abstract

We study a mechanism of symmetry transition upon compactification of a 5-dimensional field theory on S1/Z2. The transition occurs unless all components in a multiplet of a symmetry group have a common Z2 parity on S1/Z2. This mechanism is applied to a reduction of SU (5) gauge symmetry in grand unified theory, and phenomenological implications are discussed.