Proton Decay in higher dimensions

Abstract

Proton decay is used as a guiding principle for the search of a Grand unified theory. As a starting point minimal nonsupersymmetric SU(5) model is taken as it is the simplest possible grand unified model. Then modifications are discussed which ultimately leads to a supersymmetric GUT in 5 dimension. The extra dimension in this theory is compactified on a S1 / (Z2 x Z'2)orbifold. A new U(1)R symmetry is discussed which forces all 4 dimensional and five dimensional proton decay operators to be absent. But when supersymmetry breaks U(1)R symmetry breaks to R-Parity and hence makes the five dimensional operators nonzero. An estimate of proton lifetime based on this 5 dimensional operator is calculated which constraints the magnitude of the radius of compactification of the extra dimension.