Quark masses and mixing angles from universal seesaw mechanism

Aharon Davidson, Stefano Ranfone, Kameshwar C. Wali

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


A universal seesaw mechanism is invoked to account for the observed fermion mass hierarchies. In the framework of left-right symmetry, heavy fermions (mass scale) which are SU(2)LSU(2)R singlets are postulated while retaining the simplest possible Higgs system: namely, (1,2,1)+1(1,1,2)+1 accompanied by a left-right singlet (1,1,1)0 in the standard SU(3)CSU(2)LSU(2)R×U(1)B-L notation. Every conventional quark and lepton is accompanied by a nonmirror singlet heavy fermion, so that the associated mass matrix is doubled and has the seesaw form usually associated only with the neutrino mass matrix. In the single-generation case, the model provides a plausible explanation for the mass hierarchy me,u,d10-4MW and predicts memRme2, thus accounting for the superlightness of neutrinos. Combined with a U(1) axial symmetry, the mechanism provides a formalism in which the generations are distinguished and constraints emerge on the allowed form of mass matrices. In this paper, we consider the realistic case of three generations in a simplified version of the model in which CP violation does not arise from the gauge sector. Choosing the U(1)A quantum numbers so that the mass matrices are of the Fritzsch type, we calculate experimentally measured Cabibbo-Kobayashi-Maskawa matrix elements Vus, Vub, and Vcs and derive their dependence on quark mass parameters. An interesting correlation between Vus which measures the Cabibbo angle and Vub which measures the charmless decay of the b quark emerges from the model. Vub is naturally suppressed if Vus=ds-uc to a very good approximation.

Original languageEnglish
Pages (from-to)208-218
Number of pages11
JournalPhysical Review D
Issue number1
StatePublished - 1 Jan 1990

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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