Top-bottom mass hierarchy, s-mu puzzle and gauge coupling unification with split multiplets

Abstract

Supersymmetric 5D SU(5) grand unification is considered. SU(5) is broken down to G(SM) = SU(3) x SU(2) x U(1) by the Z(2) x Z'(2) assignment of the bulk field(s). The matter fields are located at the fixed point(s). In the bulk, a Higgs multiplet (5) over bar (H) (containing the bottom doublet H-1) and the SU(5) gauge multiplet are located. At one fixed point, H-2 (the top doublet) and the standard model matter multiplets are presented. Because of the difference of the locations of H-1 and H-2, one can obtain a hierarchy between top and bottom Yukawa couplings. We also present a possible way to understand the s-mu mass puzzle in this framework of the split multiplet.