Large Rparity violating couplings and grand unification
Abstract
We consider the possibility that Rparity violating interactions of particles which do not involve the first generation have large (up to 1) coupling constants, λ. Such couplings, if they exist, could have a number of phenomenological consequences: renormalization of the b  τ mass ratio, generation of ν_{τ} mass in the MeV region, etc. In grand unified models, where B and Lviolating couplings appear simultaneously, proton decay can be forbidden in virtue of the hierarchical flavor structure of λ. However, due to CabibboKobayashiMaskawa mixing this decay is induced already at one loop. Present experimental data give the upper bound λ ⪅ 10 ^{8} (or  λ' λ″ ⪅ 7 × 10 ^{16}, on products of certain L and Bviolating coupling constants, in a more general context). The bound can be avoided if there is an asymmetry between the L and Bviolating couplings of the usual matter fields. In the SU(5) model the asymmetry can be related to the doublettriplet splitting.
 Publication:

Nuclear Physics B
 Pub Date:
 February 1996
 DOI:
 10.1016/05503213(95)00615X
 arXiv:
 arXiv:hepph/9506416
 Bibcode:
 1996NuPhB.460...37S
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 Version published after revision. A discussion of the pattern of the sneutrino vacuum expectation values has been added