arXiv subjects

A. Sil

Publications and source records attributed to A. Sil.

5 recordsLinked to original sources

arXiv2015

Neutrino Masses and Deviation from Tri-bimaximal mixing in Δ(27) model with Inverse Seesaw Mechanism

We propose a scheme, based on Δ(27) flavor symmetry and supplemented by other discrete symmetries and inverse seesaw mechanism, where both the light neutrino masses and the deviation from tri-bimaximal mixing matrix can be linked to the source of lepton number violation. The hierarchies of the charged leptons are explained. We find that the quark masses including their hierarchies and the mixing can also be constructed in a similar way.

hep-ph↗

arXiv2014

Constraining a scalar field dark energy with variable equation of state for matter

The red-shift $z_{eq}$, marking the end of radiation era and the beginning of matter-dominated era, can play an important role to reconstruct dark-energy models. A variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model is proposed to estimate $z_{eq}$ in dark energy models and hence its viability. Two one-parameter models with minimally coupled scalar fields playing the role of dark energy are chosen to demonstrate this point. It is found that for desired late time behavior of the models, the estimated value of $z_{eq}$ is highly sensitive on the value of the parameter in each of these models.

gr-qc↗

arXiv2014

Interacting holographic dark energy models: A general approach

Dark energy models inspired by the cosmological holographic principle are studied in homogeneous isotropic spacetime with a general choice for the dark energy density $ρ_d=3(αH^2+β\dot{H})$. Special choices of the parameters enable us to obtain three different holographic models, including the holographic Ricci dark energy(RDE) model. Effect of interaction between dark matter and dark energy on the dynamics of those models are investigated for different popular forms of interaction. It is found that crossing of phantom divide can be avoided in RDE models for $β>0.5$ irrespective of the presence of interaction. A choice of $α=1$ and $β=2/3$ leads to a varying $Λ$-like model introducing an IR cutoff length $Λ^{-1/2}$. It is concluded that among the popular choices an interaction of the form $Q\propto Hρ_m$ suits the best in avoiding the coincidence problem in this model.

gr-qc↗

arXiv2012

The coincidence problem in $f(R)$ gravity models

To explore possibilities of avoiding coincidence problem in $f(R)$ gravity we consider models in Einstein conformal frame which are equivalent to Einstein gravity with a minimally coupled scalar field. As the conformal factor determines the coupling term and hence the interaction between matter and dark energy, the function $f(R)$ can in principle be determined by choosing an appropriate function for the deceleration parameter only. Possible behavior of $f(R)$ to avoid coincidence problem are investigated in two such cases.

gr-qc↗

arXiv2008

A Better Way to Reconstruct Dark Energy Models ?

To reconstruct dark energy models the redshift $z_{eq}$, marking the end of radiation era and the beginning of matter-dominated era, can play a role as important as $z_{t}$, the redshift at which deceleration parameter experiences a signature flip. To implement the idea we propose a variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model. A popular $Λ\propto ρ$ dark energy model is chosen for demonstration but found to be unacceptable. An alternative $Λ\propto ρa^{3}$ model is proposed and found to be more close to observation.

gr-qc↗