||Hierarchy problem, gauge coupling unification at the Planck scale, and vacuum stability
Haba, Naoyuki ,
Ishida, Hiroyuki ,
Takahashi, RyoYamaguchi, Yuya
258 , 2015-11 , Elsevier
From the point of view of the gauge hierarchy problem, introducing an intermediate scale in addition to TeV scale and the Planck scale (M-Pl = 2.4 x10(18) GeV) is unfavorable. In that way, a gauge coupling unification (GCU) is expected to be realized at M-P1. We explore possibilities of GCU at M-Pl by adding a few extra particles with TeV scale mass into the standard model (SM). When extra particles are fermions and scalars (only fermions) with the same mass, the GCU at M-Pl can (not) be realized. On the other hand, when extra fermions have different masses, the GCU can be realized around root 8 pi M-Pl without extra scalars. This simple SM extension has two advantages that a vacuum becomes stable up to M-Pl(root 8 pi M-Pl) and a proton lifetime becomes much longer than an experimental bound. (C) 2015 The Authors. Published by Elsevier B.V.