Naturalness of parity breaking in a supersymmetric SO(10) model

We consider a supersymmetric SO(10) model which remains renormalisable upto Planck scale. The cosmology of such a model passes through a Left-Right symmetric phase. Potential problems associated with domain walls can be evaded if parity breaking is induced by soft terms when supersymmetry breaks in the hidden sector. The smallness of this breaking permits a brief period of domination by the domain walls ensuring dilution of gravitinos and other unwanted relics. The requirement that domain walls disappear constrains some of the soft parameters of the Higgs potential.Comment: 4 pages, To appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

Spontaneous Left-Right Symmetry Breaking in Supersymmetric Models with only Higgs Doublets

We studied the question of parity breaking in a supersymmetric left-right model, in which the left-right symmetry is broken with Higgs doublets (carrying $B-L=\pm 1$). Unlike the left-right symmetric models with triplet Higgs scalars (carrying $B-L=\pm 2$), in this model it is possible to break parity spontaneously by adding a parity odd singlet. We then discussed how neutrino mass of type III seesaw can be invoked in this model by adding extra fermion singlets. We considered simple forms of the mass matrices that are consistent with the unification scheme and demonstrate how they can reproduce the required neutrino mixing matrix. In this model, the baryon asymmetry of the universe is generated via leptogenesis. The required mass scales in the model is then found to be consistent with the gauge coupling unification.Comment: 19 pages, 1 eps figur

Cosmology in a supersymmetric model with gauged B−LB-L

We consider salient cosmological features of a supersymmetric model which is Left-Right symmetric and therefore possessing gauged $B-L$ symmetry. The requirement of breaking parity and also obtaining charge preserving vacua introduces some unique features to this model (MSLRM), resulting in a preference for non-thermal Leptogenesis. Assuming that the model preserves TeV scale supersymmetry, we show that the vacuum structure generically possesses domain walls, which can serve two important purposes. They can signal a secondary inflation required to remove unwanted relics such as gravitino and moduli and also generate lepton asymmetry by a mechanism similar to electroweak baryogenesis. The requirement of disappearance of domain walls imposes constraints on the soft parameters of the theory, testable at the TeV scale. We also propose an alternative model with spontaneous parity violation (MSLR\rlap/P). Incorporating the same cosmological considerations in this case entails constraints on a different set of soft parameters.Comment: 18 pages. Minor changes in text, but conclusion remains same. Published in Phys. Rev.

Gauge mediated supersymmetry breaking and the cosmology of Left-Right symmetric model

Left-Right symmetry including supersymmetry presents an important class of gauge models which may possess natural solutions to many issues of phenomenology. Cosmology of such models indicates a phase transition accompanied by domain walls. Such walls must be unstable in order to not conflict with standard cosmology, and can further be shown to assist with open issues of cosmology such as dilution of unwanted relic densities and leptogenesis. In this paper we construct a model of gauge mediated supersymmetry breaking in which parity breaking is also signalled along with supersymmetry breaking and so as to be consistent with cosmological requirements. It is shown that addressing all the stated cosmological issues requires an extent of fine tuning, while in the absence of fine tuning, leptogenesis accompanying successful completion of the phase transition is still viable