Ng. Deshpande et al., TOWARDS A VIABLE GRAND MODEL WITH M(G)SIMILAR-TO-M(STRING) AND MI-SIMILAR-TO-10(12) GEV, Physics letters. Section B, 384(1-4), 1996, pp. 116-122
We present a model based on the gauge group SU(2)(L)xSU(2)(R)xSU(4)(C)
with gauge couplings that are found to be unified at a scale MG near
the string unification scale. The model breaks to the minimal supersym
metric standard model at a scale M(I) similar to 10(12) GeV, which is
instrumental in producing a neutrino in a mass range that can serve as
hot dark matter and this scale can also solve the strong CP problem v
ia the Peccei-Quinn (PQ) mechanism with an invisible harmless axion. W
e show how this model can accommodate low and high values of tan beta
and ''exotic'' representations that often occur in string derived mode
ls. We show that this model has lepton flavor violation which can lead
to processes which are one or two orders of magnitude below the curre
nt experimental limits.