R. N. Mishra

Bio: R. N. Mishra is an academic researcher from Ravenshaw University. The author has contributed to research in topics: Quark & Nucleon. The author has an hindex of 5, co-authored 12 publications receiving 124 citations.

Hyperon stars in a modified quark meson coupling model

Abstract: We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $\ensuremath{\sigma},\phantom{\rule{0.16em}{0ex}}\ensuremath{\omega}$, and $\ensuremath{\rho}$ mesons through mean-field approximations. The effect of a nonlinear $\ensuremath{\omega}\text{\ensuremath{-}}\ensuremath{\rho}$ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of $2\phantom{\rule{4pt}{0ex}}{\mathrm{M}}_{\ensuremath{\bigodot}}$ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear $\ensuremath{\omega}\text{\ensuremath{-}}\ensuremath{\rho}$ term in the context of obtaining the star mass constraint in the present set of parametrizations.

Nuclear symmetry energy in a modified quark meson coupling model

Abstract: We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to $\sigma$, $\omega$, and $\rho$ mesons through mean-field approximations. We find an analytic expression for the symmetry energy ${\cal E}_{sym}$ as a function of its slope $L$. Our result establishes a linear correlation between $L$ and ${\cal E}_{sym}$. We also analyze the constraint on neutron star radii in $(pn)$ matter with $\beta$ equilibrium.

Diluted magnetic ferroelectric effect in BaTi0.9Hf0.05Co0.05O3 ceramic

Abstract: We report that magnetism, especially ferromagnetism, can be induced in a nonmagnetic ferroelectric oxide such as barium titanate (BaTiO3) with choosing of suitable dopants. High-density polycrystalline sample of BaTi0.9Hf0.05Co0.05O3 was prepared using solid-state sintering route, and the effect of Co and Hf substitution on structural, magnetic and ferroelectric properties of BaTiO3 was studied. The magnetic order obtained in the above sample is of intrinsic in nature. Ferromagnetic behavior shown in the BaTi0.9Hf0.05Co0.05O3 ceramic may be attributed to the effective exchange interactions between oxygen vacancies and Co ions. BaTi0.9Hf0.05Co0.05O3 ceramic has also shown ferroelectric (lossy type) behavior.

Pairing mechanism in Fe-based superconductors

Abstract: I review recent works on the symmetry and the structure of the superconducting gap in Fe-based superconductors and on the underlying pairing mechanism in these systems. The experimental data on superconductivity show very rich behavior, with potentially different symmetry of a superconducting state for different compositions of the same material. The variety of different pairing states raised the issue whether the physics of Fe-based superconductors is model-dependent or is universal, governed by a single underlying pairing mechanism. I argue that the physics is universal and that all pairing states obtained so far can be understood within the same universal pairing scenario and are well described by the effective low-energy model with a small number of input parameters.

Perspectives and challenges in multilayer ceramic capacitors for next generation electronics

Abstract: The multilayered ceramic capacitor (MLCC) is a key component of electronic equipment, such as smartphones, portable PCs and electric vehicles, which contain a number of MLCCs. As MLCCs distribute and control the amount of current flowing through circuits, remove noise, and prevent malfunction, MLCCs play a key role in enabling electronic devices to have high performance, multi-functionality, and high integration. This review highlights the critical issues and recent progress in developing highly volumetric-efficient and high capacitance MLCCs from the viewpoint of designing a BaTiO3-based dielectric layer. After a brief introduction of MLCCs and dielectric materials, we summarize the current issues in developing BaTiO3-based dielectric materials for MLCCs with high performance and reliability and describe the strategies to optimize dielectric properties through nano/microstructure control, chemical modification and doping. Finally, we provide an outlook on the development and future application of MLCCs. It is anticipated that this review can serve as an overview and evaluation of state-of-the-art synthesis and design of BaTiO3-based dielectric materials for MLCC applications.

Neutron Star Equation of State from the Quark Level in Light of GW170817

Abstract: The matter state inside neutron stars (NSs) is an exciting problem in astrophysics, nuclear physics, and particle physics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. We propose a new NS EOS, “QMF18,” from the quark level, which describes robust observational constraints from a free-space nucleon, nuclear matter saturation, heavy pulsar measurements, and the tidal deformability of the very recent GW170817 observation. For this purpose, we employ the quark mean-field model, which allows us to tune the density dependence of the symmetry energy and effectively study its correlations with the Love number and the tidal deformability. We provide tabulated data for the new EOS and compare it with other recent EOSs from various many-body frameworks.

Neutron star equation of state from the quark level in the light of GW170817

Abstract: Matter state inside neutron stars is an exciting problem in astrophysics, nuclear physics and particle physics. The equation of state (EOS) of neutron stars plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. We propose a new neutron star EOS "QMF18" from the quark level, which describes well robust observational constraints from free-space nucleon, nuclear matter saturation, heavy pulsar measurements and the tidal deformability of the very recent GW170817 observation. For this purpose, we employ the quark-mean-field (QMF) model, allowing one to tune the density dependence of the symmetry energy and study effectively its correlations with the Love number and the tidal deformability. We provide tabulated data for the new EOS and compare it with other recent EOSs from various many-body frameworks.

Classical simulation of relativistic quantum mechanics in periodic optical structures

Abstract: Spatial and/or temporal propagation of light waves in periodic optical structures offers a unique possibility to realize in a purely classical setting the optical analogues of a wide variety of quantum phenomena rooted in relativistic wave equations. In this work a brief overview of a few optical analogues of relativistic quantum phenomena, based either on spatial light transport in engineered photonic lattices or on temporal pulse propagation in Bragg grating structures, is presented. Examples include spatial and temporal photonic analogues of the Zitterbewegung of a relativistic electron, Klein tunneling, vacuum decay and pair production, the Dirac oscillator, the relativistic Kronig–Penney model, and optical realizations of non-Hermitian extensions of relativistic wave equations.