1010.6289

Even after losing enthusiasm after going through tedious peer review process, I finished the latest work (and first with my supervisor :P) and it has come on arXiv.org today with the reference number in the title of this post. It is about gauge coupling unification, fermion mass universality and type I seesaw dominance in supersymmetric left-right models with natural conservation of R-parity. The abelian B-L gauge symmetry is broken by Higgs triplet fields with B-L charge 2 and hence R-parity defined as

is conserved. The good thing about this is the natural presence of stable cold dark matter candidate in the model in terms of the lightest supersymmetric particle (LSP). Anyway our focus is not on this issue. We have found that at the cost of adding a few extra superfields, the minimal version of such models give rise to gauge coupling unification (at very high scale in agreement with proton decay constraints) as well fermion mass unification. The fermion mass unification relations in SO(10) grand unified model are

What we find is that fermion mass unification is achieved properly only in the case of third (and hence the heaviest) family of fermions whereas there is some discrepancy in the case of lighter fermions. However such issues can be handled with proper threshold corrections which can be found in the literature. Good thing is that such good characteristics of gauge coupling unification and fermion mass universality can be achieved in a left-right model only which is tremendously simpler than a GUT model like SO(10). But of course SO(10) has its own charm and can't be ignored. The point is that, the desert below the GUT symmetry breaking scale at very high scale is ruled by the effective supersymmetric left right model with some additional light superfields which are part of the SO(10) gauge structure but remained light somehow till the TeV scale (for example). Our approach was bottom up in this case, however it will be good to realize this in a top-down approach. That's the goal of next project.