Conditions for suppressing dimension-five proton decay in renormalizable SUSY SO(10) GUT

Abstract

The SUSY SO(10) GUT is in severe tension with the experimental bounds on proton partial lifetimes because proton decay mediated by colored Higgsinos (dimension-five proton decay) is too rapid. In this paper, we pursue the possibility that a texture of the Yukawa coupling matrices in a renormalizable SUSY SO(10) GUT model suppresses dimension-five proton decay. We focus on a general renormalizable SUSY SO(10) GUT model which contains 10 + 126 + overline{textbf{126}} + 120 representation fields and where the Yukawa coupling matrices of the 16 matter fields with the 10, overline{textbf{126}} , 120 fields, Y10, Y126, Y120, provide the quark and lepton Yukawa couplings and Majorana mass of the singlet neutrinos. We find that if components in certain flavor bases, {left({Y}_{10}right)}_{u_R{d}_R} , {left({Y}_{126}right)}_{u_R{d}_R} , {left({Y}_{10}right)}_{u_R{s}_R} , {left({Y}_{126}right)}_{u_R{s}_R} , {left({Y}_{10}right)}_{u_L{d}_L} , {left({Y}_{126}right)}_{u_L{d}_L} , {left({Y}_{10}right)}_{u_L{s}_L} , {left({Y}_{126}right)}_{u_L{s}_L} , {left({Y}_{10}right)}_{u_L{u}_L} , {left({Y}_{126}right)}_{u_L{u}_L} , are all on the order of the up quark Yukawa coupling, dimension-five proton decay can be suppressed while the Yukawa coupling matrices still reproduce the realistic quark and lepton masses and flavor mixings. We numerically obtain specific Yukawa coupling matrices satisfying the above conditions, calculate proton partial lifetimes from them and evaluate how dimension-five proton decay is suppressed when these conditions are met.