Singlet fermion Dark Matter within Left-Right Model

We discuss singlet fermion dark matter within a left-right symmetric model promoting baryon and lepton numbers as separate gauge symmetries. We add a simple Dirac fermionic dark matter singlet under $SU(2)_{L,R}$ with nonzero and equal baryon and lepton number which ensures electric charge neutrality. Such a dark matter candidate interacts with SM particles through the extra $Z_{B,\ell}$ gauge bosons. This can give rise to a dark matter particle of a few hundred GeV that couples to $\sim$ TeV scale gauge bosons to give the correct relic density. This model thus accommodates TeV scale $Z_{B,\ell}$ gauge bosons and other low scale BSM particles, which can be easily probed at LHC.Comment: Discussions added for dark matter direct and indirect detection constraints. Accepted for publication in Phys. Lett.

Type III Seesaw and Dark Matter in a Supersymmetric Left-Right Model

We propose a new supersymmetric left right model with Higgs doublets carrying odd B-L charge, higgs bidoublet and heavy Higgs triplets with zero B-L charge and a set of sterile neutrinos which are singlet under the gauge group. We show that spontaneous parity violation can be achieved naturally in this model and the neutrino masses arise from the so called type III seesaw mechanism. We also discuss the possible phenomenology in the context of neutrino masses and dark matter

Post-Sphaleron baryogenesis and n−nˉn-\bar{n} oscillation in non-SUSY SO(10) GUT with gauge coupling unification and proton decay

Post-sphaleron baryogenesis, a fresh and profound mechanism of baryogenesis accounts for the matter-antimatter asymmetry of our present universe in a framework of Pati-Salam symmetry. We attempt here to embed this mechanism in a non-SUSY SO(10) grand unified theory by reviving a novel symmetry breaking chain with Pati-Salam symmetry as an intermediate symmetry breaking step and as well to address post-sphaleron baryogenesis and neutron-antineutron oscillation in a rational manner. The Pati-Salam symmetry based on the gauge group $SU(2)_L \times SU(2)_{R} \times SU(4)_C$ is realized in our model at $10^{5}-10^{6}$ GeV and the mixing time for the neutron-antineutron oscillation process having $\Delta B=2$ is found to be \tau_{n-\bar{n}} \simeq 10^{8}-10^{10}\,\mbox{secs} with the model parameters which is within the reach of forthcoming experiments. Other novel features of the model includes low scale right-handed $W^{\pm}_R$, $Z_R$ gauge bosons, explanation for neutrino oscillation data via gauged inverse (or extended) seesaw mechanism and most importantly TeV scale color sextet scalar particles responsible for observable $n-\bar{n}$ oscillation which can be accessible to LHC. We also look after gauge coupling unification and estimation of proton life-time with and without the addition of color sextet scalars.Comment: v2: 28 pages, matches the version to be published in European Physical Journal

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