If left-right gauge theory occurs as an intermediate symmetry in a GUT then,
apart from other advantages, it is possible to obtain the see-saw scale
necessary to understand small neutrino masses with Majorana coupling of order
unity. Barring threshold or non-renormalizable gravitational effects, or
assumed presence of additional light scalar particles of unprescribed origin,
all other attempts to achieve manifest one-loop gauge coupling unification in
SUSY SO(10) with left-right intermediate symmetry have not been successful so
far. Attributing this failure to lack of flavor symmetry in the GUT, we show
how the spontaneous symmetry breaking of SO(10)ΓS4β leads to such
intermediate scale extending over a wide range, MRββ5Γ109 GeV
to 1015 GeV. All the charged fermion masses are fitted at the see-saw
scale, MNββMRββ4Γ1013 GeV which is obtained with
Majorana coupling f0ββ1. Using a constrained parametrization in which
CP-violation originates only from quark sector, besides other predictions made
in the neutrino sector, the reactor mixing angle is found to be ΞΈ13ββ3ββ5β which is in the range accessible to ongoing and
planned experiments. The leptonic Dirac phase turns out to be Ξ΄βΌ2.9β3.1 radians with Jarlskog invariant JβΌ2.95Γ10β5β10β3.Comment: Minor clarification and few references added to match the published
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