Sneutrino vevs : Key to Susy Unification and Cosmology

Due to the intimate connection between R-parity and 
B-L symmetry, the question of whether sneutrino vevs do or do not 
obtain, and keep, an expectation value plays a key role in 
differentiating Supersymmetric unified models and their 
cosmology. We showed that sneutrino vevs must vanish in 
renormalizable models that incorporate the Seesaw  mechanism. Then 
R-parity is preserved to low energies so that the LSP is stable and 
thus an ideal dark matter candidate. Such LR Supersymmetric Seesaw 
models unify within 126-plet Higgs containing (and thus `unstrung') 
Susy SO(10) GUTs that fit all known fermion data without invoking 
non-renormalizable operators. Fermion fits in terms of GUT 
parameters lead to distinctive predictions regarding sfermion 
spectra such as the prediction of a large A0 parameter and normal 
s-hierarchy. On the other hand, sneutrino type odd B-L vevs are 
generic to the plethora of `stringy' SO(10) models that utilize 
16-plet Higgs vevs and singlets and violate R-parity maximally. Such 
models utilize `composite 126-plets' and non-renormalizable 
operators to fit the fermion phenomenology. Recently an early epoch 
of sneutrino vevs has  been identified as enabling primordial 
Supersymmetric  inflection  based on the NLH flat direction of the MSSM.