Arnab Dasgupta

Galactic Center Gamma Ray Excess in a Radiative Neutrino Mass Model

Abstract The Fermi gamma ray space telescope data have pointed towards an excess of gamma rays with a peak around 1 – 3 GeV in the region surrounding the galactic center. This anomalous excess can be described well by a dark matter candidate having mass in the range 31 – 40 GeV annihilating into b b ¯ pairs with a cross section of 〈 σ v 〉 ≃ ( 1.4 – 2.0 ) × 10 − 26 cm 3 / s . In this work we explore the possibility of having such a dark matter candidate within the framework of a radiative neutrino mass model. The model is a simple extension of the standard model by an additional U ( 1 ) X gauge symmetry where the standard model neutrino masses arise both at tree level as well as radiatively by the anomaly free addition of one singlet fermion N R and two triplet fermions Σ 1 R , Σ 2 R with suitable Higgs scalars. The spontaneous gauge symmetry breaking is achieved in such a way which results in a residual Z 2 symmetry hence providing a stable cold dark matter candidate. We show that the singlet fermionic dark matter candidate in our model can give rise to the galactic center gamma ray excess. The parameter space which simultaneously satisfies the constraints on relic density, direct detection scattering as well as collider bounds essentially corresponds to an s-wave resonance where the gauge boson mass m X is approximately twice that of dark matter mass m χ . We also discuss the compatibility of such a light fermion singlet dark matter with light neutrino mass.

Naturally light Dirac neutrino in Left-Right Symmetric Model

We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw mechanism due to the presence of additional vector like fermions. The neutrinos acquire a one-loop Dirac mass from the same additional vector like charged leptons without requiring any additional discrete symmetries. The model can also be extended by an additional

Discovery potential of T2K and NOvA in the presence of a light sterile neutrino

Z_2

Neutrinoless double beta decay in type I+II seesaw models

symmetry in order to have a scotogenic version of this scenario predicting a stable dark matter candidate. We show that the latest Planck upper bound on the effective number of relativistic degrees of freedom

Common Origin of Neutrino Mass, Dark Matter and Dirac Leptogenesis

N_{\text{eff}}=3.15 \pm 0.23

Multi-component fermionic dark matter and IceCube PeV scale neutrinos in left-right model with gauge unification

tightly constrains the right sector gauge boson masses to be heavier than 3.548 TeV. This bound on gauge boson mass also affects the allowed values of right scalar doublet dark matter mass from the requirement of satisfying the Planck bound on dark matter relic abundance. We also discuss the possible implications of such a scenario in charged lepton flavour violation and generating observable electric dipole moment of leptons.

Charged lepton flavour violcxmation and neutrinoless double beta decay in left-right symmetric models with type I+II seesaw

A bstractWe study the impact of one light sterile neutrino on the prospective data expected to come from the two presently running long-baseline experiments T2K and NOvA when they will accumulate their full planned exposure. Introducing for the first time, the bi-probability representation in the 4-flavor framework, commonly used in the 3-flavor scenario, we present a detailed discussion of the behavior of the vμ → ve and v¯μ→v¯e

Common origin of the 3.55 keV x-ray line and the Galactic Center gamma-ray excess in a radiative neutrino mass model

{\overline{v}}_{\mu}\to {\overline{v}}_e