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

Sub-dominant Type II Seesaw as an Origin of Non-zero θ13\theta_{13} in SO(10) model with TeV scale Z′Z^\prime Gauge Boson

We discuss a class of left-right symmetric models where the light neutrino masses originate dominantly from type I seesaw mechanism along with a sub-dominant type II seesaw contribution. The dominant type I seesaw gives rise to tri-bimaximal type neutrino mixing whereas sub-dominant type II seesaw acts as a small perturbation giving rise to non-zero $\theta_{13}$ in our model which also has TeV scale right-handed neutrinos and $Z^\prime$ gauge boson thereby making the model verifiable at current accelerator experiments. Sub-dominant type II and dominant type I seesaw can be naturally accommodated by allowing spontaneous breaking of D-parity and $SU(2)_R$ gauge symmetry at high scale and allowing TeV scale breaking of $U(1)_{R} \times U(1)_{B-L}$ into $U(1)_Y$. We also embed the left-right model in a non-supersymmetric $SO(10)$ grand unified theory (GUT) with verifiable TeV scale $Z^\prime$ gauge boson. Drawing it to an end, we scrutinize in detail the evaluation of one-loop renormalization group evolution for relevant gauge couplings and estimation of the proton life time which can be accessible to the foreseeable experiments. And in the aftermost part we make an estimation of branching ratio for lepton flavor violating process $\mu \rightarrow e + \gamma$ as a function of type II seesaw strength due to doubly charged component of the right handed Higgs triplet with mass at the TeV scale, which can be accessible at ongoing experiments.Comment: v2: 30 pages, 8 figures, minor revision, matches the version to be published in Nuclear Physics

Determining neutrino mass hierarchy in an extended Left-Right model

We derive the lower bound on absolute scale of lightest neutrino mass for normal hierarchy and inverted hierarchy pattern of light neutrinos by studying the new physics contributions to charged lepton flavour violating decays and neutrinoless double beta decay in the framework of a TeV scale left-right symmetric model. Neutrino mass is generated in the model via type-II seesaw dominance with the help of a heavy sterile neutrino. This scenario allows large light-heavy neutrino mixing and the mixing facilitates new channels for neutrinoless double beta decay and lepton flavour violating decays. We express all the model parameters in terms of oscillation parameters in order to constrain light neutrino mass scale and extract information on neutrino mass hierarchy.Comment: 5 pages, 5 figures, 3 tables, 20th Conference on Flavor Physics and CP Violatio