arXiv subjects

M. Sruthilaya

Publications and source records attributed to M. Sruthilaya.

3 recordsLinked to original sources

arXiv2017

$A_4$ realization of Linear Seesaw and Neutrino Phenomenology

Motivated by the crucial role played by the discrete flavour symmetry groups in explaining the observed neutrino oscillation data, we consider the $A_4$ realization of linear seesaw by extending the standard model (SM) particle content with two types of right-handed neutrinos along with the flavon fields, and the SM symmetry with $A_4\times Z_4\times Z_2$ and a global symmetry $U(1)_X$ which is broken explicitly by the Higgs potential. We scrutinize whether this model can explain the recent results from neutrino oscillation experiments by searching for parameter space that can accommodate the observables such as the reactor mixing angle $θ_{13}$, the CP violating phase $δ_{CP}$, sum of active neutrino masses $Σ_{i} m_i$, solar and atmospheric mass squared differences, and the lepton number violating parameter called as effective Majorana mass parameter, in line with recent experimental results. We also discuss the scope of this model to explain the baryon asymmetry of the universe through Leptogenesis. We also investigate the possibility of probing the non-unitarity effect in this scenario, but it is found to be rather small.

hep-ph↗

arXiv2017

Neutrino Mass and Neutrinoless double beta decay in SO(10) GUT with Pati-Salam symmetry

We demonstrate how a class of non-supersymmetric $SO(10)$ GUT with asymmetric left-right theory $SU(2)_L \times U(1)_R \times U(1)_{B-L} \times SU(3)_C$ and Pati-Salam theory $SU(2)_L \times SU(2)_R \times SU(4)_C$ as intermediate symmetry breaking steps leads to successful gauge coupling unification satisfying proton decay constraints. The motivation behind this work is two fold: firstly to study the renormalization group evolution equations for gauge couplings by keeping right-handed neutral gauge boson $Z_R$ around LHC energy range leading interesting dilepton searches at collider while fixing charge partner of the gauge boson $W_R$ at very high scale; secondly to explain neutrino masses and associated lepton number violating process like neutrinoless double beta decay in three possible cases depending on how $SU(2)_L \times U(1)_R \times U(1)_{B-L} \times SU(3)_C$ breaks down to SM. We include one extra fermion singlet per generation in order to implement gauged extended seesaw where light neutrino mass is governed by natural type-II seesaw mechanism whereas type-I seesaw contribution is exactly canceled out. Since light neutrino mass formula is independent of Dirac neutrino mass matrix, the value of Dirac neutrino mass is taken to be up-type quark mass matrix which is a characteristics of Pati-Salam symmetry relating quarks with leptons. We present analytic relation for effective Majorana mass parameter and corresponding half-life arising from new physics contributions due to purely left-handed currents through exchange of heavy right-handed neutrinos and sterile neutrinos. We numerically estimate effective Majorana mass parameter and half-life vs. lightest neutrino mass and derive lower bound on lightest neutrino mass by saturating with experimental bounds like GERDA Phase-II, KamLANDZen and EXO.

hep-ph↗

arXiv2016

Perturbation to TBM mixing and its phenomenological implications

To accommodate the recently observed non-zero reactor mixing angle $θ_{13}$, we consider the lepton mixing matrix as Tri-bimaximal mixing (TBM) form in the leading order along with a perturbation in neutrino sector. The perturbation is taken to be a rotation in 23 plane followed by a rotation in 13 plane, i.e., $R_{23}(θ_{23}')R_{13}(θ_{13}',ϕ)$. We obtain the allowed values of the parameters $θ_{23}'$, $θ_{13}'$ and $ϕ$, which can accommodate all the observed mixing angles consistently and calculate the phenomenological observables such as the Dirac CP violating phase ($δ_{CP}$), Jarlskog invariant ($J_{CP}$), effective majorana mass $M_{ee}^ν$, and $m_{ν_e}$, the electron neutrino mass. We find that $δ_{CP}$ can take any values between $0$ and $-π/2$ and $M_{ee}^ν$ always comes below its experimental upper limit.

hep-ph↗