arXiv subjects

D. Jain

Publications and source records attributed to D. Jain.

5 recordsLinked to original sources

arXiv2023

Reply to the "Comment on `Effect of density and nucleon-nucleon potential on the fusion cross section within the relativistic mean field formalism'"

In reply to the Comment made by M. V. Chushnyakova et al. on our paper [Phys. Rev. C 101, 044603 (2020)], we argue that the calculations, results and conclusions of our paper remain valid. We have shown here the calculations for one reaction using the deformed densities and the R3Y nucleon-nucleon potential obtained within the relativistic mean-field (RMF) formalism. Suitable clarications and justifications are given to address all the points raised in the Comment.

nucl-th↗

arXiv2009

Constraining dark matter-dark energy interaction with gas mass fraction in galaxy clusters

The recent observational evidence for the current cosmic acceleration have stimulated renewed interest in alternative cosmologies, such as scenarios with interaction in the dark sector (dark matter and dark energy). In general, such models contain an unknown negative-pressure dark component coupled with the pressureless dark matter and/or with the baryons that results in an evolution for the Universe rather different from the one predicted by the standard $Λ$CDM model. In this work we test the observational viability of such scenarios by using the most recent galaxy cluster gas mass fraction versus redshift data (42 X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.063 < z < 1.063) (Allen et al. 2008) to place bounds on the parameter $ε$ that characterizes the dark matter/dark energy coupling. The resulting are consistent with, and typically as constraining as, those derived from other cosmological data. Although a time-independent cosmological constant ($Λ$CDM model) is a good fit to these galaxy cluster data, an interacting dark energy component cannot yet be ruled out.

astro-ph.CO↗

arXiv2009

Field dependent competing magnetic ordering in multiferroic Ni3V2O8

The geometrically frustrated magnet Ni3V2O8 undergoes a series of competing magnetic ordering at low temperatures. Most importantly, one of the incommensurate phases has been reported to develop a ferroelectric correlation caused by spin frustration. Here we report an extensive thermodynamic, dielectric and magnetic study on clean polycrystalline samples of this novel multiferroic compound. Our low temperature specific heat data at high fields up to 14 Tesla clearly identify the development of a new magnetic field induced phase transition below 2 K that shows signatures of simultaneous electric ordering. We also report temperature and field dependent dielectric constant that enables us to quantitatively estimate the strength of magneto-electric coupling in this improper ferroelectric material.

cond-mat.mtrl-sci↗

arXiv2008

Delicate f(R) gravity models with disappearing cosmological constant and observational constraints on the model parameters

We study the $f(R)$ theory of gravity using metric approach. In particular we investigate the recently proposed model by Hu-Sawicki, Appleby $-$ Battye and Starobinsky. In this model, the cosmological constant is zero in flat space time. The model passes both the Solar system and the laboratory tests. But the model parameters need to be fine tuned to avoid the finite time singularity recently pointed in the literature. We check the concordance of this model with the $H(z)$ and baryon acoustic oscillation data. We find that the model resembles the $Λ$CDM at high redshift. However, for some parameter values there are variations in the expansion history of the universe at low redshift.

hep-th↗

arXiv2002

Brane World Cosmologies and Statistical Properties of Gravitational Lenses

Brane world cosmologies seem to provide an alternative explanation for the present accelerated stage of the Universe with no need to invoke either a cosmological constant or an exotic \emph{quintessence} component. In this paper we investigate statistical properties of gravitational lenses for some particular scenarios based on this large scale modification of gravity. We show that a large class of such models are compatible with the current lensing data for values of the matter density parameter $Ω_{\rm{m}} \leq 0.94$ ($1σ$). If one fixes $Ω_{\rm{m}}$ to be $\simeq 0.3$, as suggested by most of the dynamical estimates of the quantity of matter in the Universe, the predicted number of lensed quasars requires a slightly open universe with a crossover distance between the 4 and 5-dimensional gravities of the order of $1.76 H_o^{-1}$.

astro-ph↗