Horizontal symmetry and the fourth generation
Journal
Physical Review D
Journal Volume
36
Journal Issue
11
Pages
3484-3493
Date Issued
1987
Author(s)
Abstract
A systematic investigation of all possible horizontal symmetries acting on four generations of quarks in a minimal left-right-symmetric model is carried out. There are only two consistent models with realistic constraints on the quark masses and mixing angles. It is shown that Z4 is the unique symmetry group leading to these models. The fourth-generation quark masses mb and mt are constrained to be (A) mb/mtmb/mt, (B) ms/mc(mb+mb)/(mt+mt). Thus, model (A) predicts mt,mb43 GeV whereas model (B) has mb58 GeV. The two models differ in the mixing of the fourth generation into the first three. A crucial test which can distinguish the two models is a direct measurement of the mixing matrix element |Vub|. Model (A) predicts it to be 10-4, an order of magnitude smaller than the prediction of model (B). © 1987 The American Physical Society.
Type
journal article