Search

The Majorana nature of neutrinos will be the confirmed by the observation of the rare process called as neutrinoless double beta decay process, i.e. the simultaneous decay of two neutrons in the nucleus of an isotope (A, Z) into two protons and two electrons without the emission of any neutrinos i.e, $(A, Z) \to (A, Z + 2) + 2 e^-$. The non-observation of such a decay so far has been interpreted as a lower limit on the half life of the isotope under investigation, which puts severe constraints on any new physics giving rise to LNV in the electron sector. On the other hand, the standard mechanism with normal ordering and inverted ordering can not saturate the present experimental limit while quasi-degenerate light neutrinos are strongly disfavored by the upper limits on the sum of light neutrino masses from cosmological data sets. In this work, we show that how dark side of the solar neutrino parameter space and effect of new physics contributions from right-handed currents can saturate the experimental limit provided by KamLAND-Zen and GERDA., Comment: 6 pages, 2 figures

We consider a minimal renormalizable non-supersymmetric $E_6$ Grand Unified Theory using only fundamental representation $27$ for fermions and scalars. The proposed model, guided by TeV-scale vector-like fermions and scalars offer successful gauge unification even in the absence of any intermediate symmetry. Embedded with threshold corrections, it is shown to be compatible with the present experimental limit on proton decay lifetime. The unique feature of the model shows that, the GUT threshold corrections to the unification mass, is controlled by superheavy gauge bosons only, thereby minimising the uncertainty of the GUT predictions. The scalar and fermion leptoquarks residing in $27$ representation can explain flavor physics anomalies like $R(K^*)$ and $R(D^*)$ as reported by the LHCb collaboration and the muon anomalous magnetic moment reported by the recent Muon $g-2$ experiment at Fermilab. The model can also predict a sub-eV scale neutrino at one-loop level via exchange of $W$ and $Z$ gauge bosons via MRIS mechanism., 5 pages, 4 tables, 2 figures

We consider a non-supersymmetric E6 Grand Unified Theory (GUT) with intermediate trinification symmetry SU(3)C×SU(3)L×SU(3)R×D (D denoted as D-parity for discrete left-right symmetry) and study the effect of one-loop threshold corrections arising due to every class of superheavy particles (scalars, fermions and vectors). It is observed that, the intermediate mass scale MI and sin2⁡θW remain unaffected by GUT threshold contributions. The threshold modified unification mass scale MU is in excellent agreement with the present experimental proton decay constraint. The novel feature of the model is that GUT threshold uncertainty of MU is found to be controlled by superheavy scalars only, leading to a very predictive scenario for proton decay, which can be verifiable within the foreseeable experiments.

We explore an $A_4$-symmetric flavor based left-right symmetric model with linear seesaw mechanism and study the associated neutrino phenomenology. The framework offers the advantage of studying neutrino mass, non-unitarity effects in lepton sector, lepton flavour violation and CP violation. The fermion content of the model includes usual quarks, leptons along with additional sterile fermion per generation while the scalar content includes Higgs doublets and scalar bidoublet. We study analytically as well as numerically the correlation between different model parameters and their dependence on experimentally determined neutrino observables., 33 pages, 25 figures