DR RAVI KANT MISHRA
@sliet.ac.in
Professor, Department of Mathematics
Sant Longowal Institute of Engineering and Technology ( Deemed UNiversity-Under MoE-Government of india) Longowal Punjab India
RESEARCH, TEACHING, or OTHER INTERESTS
Mathematics, Physics and Astronomy, Computational Theory and Mathematics, Numerical Analysis
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
R. K. Mishra and Rahul Sharma
Springer Science and Business Media LLC
, MISHRA R.K, SHARMA RAHUL, and
Editura Academiei Române
In this research paper, we developed the theoretical framework of f(T) gravity as an alternative theory of gravity beyond general relativity (GR). We have explored its mathematical formalism, focusing on field equations and investigating its cosmological implications. We have also analyzed key parameters like expansion rate and energy density over cosmic time. The present research contributes to understanding gravity’s role in cosmic evolution, offering insight into the universe’s dynamics and the potential of f(T) gravity.
R. K. Mishra and Rahul Sharma
World Scientific Pub Co Pte Ltd
In this paper, we have presented the cosmological model in Brans–Dicke theory (BDT) of gravity for a Bianchi type-IX spacetime. We obtained the exact solutions of the field equations by applying the new form of deceleration parameter, i.e. fractional linear varying deceleration parameter (FLVDP) as proposed by R. K. Mishra and A. Chand [Astrophys. Space Sci. 361, 1 (2016)]. In this paper, we have also presented the physical and geometric properties and mathematical analysis of the proposed model. Then we have provided the energy conditions and statefinder diagnostic.
R. K. Mishra and Rahul Sharma
Springer Science and Business Media LLC
R. K. Mishra and Rahul Sharma
World Scientific Pub Co Pte Ltd
This study includes the cosmic evolution and the potential periodicity of the universe. It employs a periodic varying deceleration parameter (PVDP) within the framework of [Formula: see text] theory of gravity, with a specific focus on the Bianchi-II model. We explore the dynamic nature of the universe, with physical and geometrical properties within this theoretical framework. We have also analyzed the cosmographic parameters, including jerk, snap, and lerk, for deeper insights into the universe’s evolution and behavior. Utilizing state finder diagrams and the Om diagnostic (which illustrates the variation of [Formula: see text] with redshift) signifying a shift from matter dominance to a stronger influence of dark energy (DE), we construct a comprehensive map of the universe’s trajectory and behavior. By employing the Bianchi-II model within the [Formula: see text] theory, our proposed model helps us in understanding the universe’s oscillatory patterns and underlying mechanisms. This research significantly contributes to our understanding of cosmic evolution and periodicity within the [Formula: see text] theory.
R. K. Mishra and Navya Jain
Springer Science and Business Media LLC
, R.K. MISHRA, NAVYA JAIN, and
Editura Academiei Romane
This study examines the stability of cosmological models through perturbation theory, focusing on different formulations of the deceleration parameter (DP). By analysing the eigenvalues of perturbations, we identify key insights into the models’ long-term dynamics and stability. The results reveal the presence of stable and marginally stable modes, indicating how perturbations evolve and dissipate over cosmic time. These findings provide a deeper understanding of cosmic evolution, the formation of large-scale structures, and the behaviour of perturbations, offering significant contributions to cosmological research and theoretical modelling of the Universe.
R. K. Mishra and Navya Jain
World Scientific Pub Co Pte Ltd
The present communication explores [Formula: see text]-dimensional cosmological models within the framework of the [Formula: see text] theory. The exploration is motivated by Kaluza–Klein theory, where the existence of extra dimensions becomes a focal point in understanding the fundamental forces of the universe. A cosmological model has been constructed by assuming Fractional quadratic deceleration parameter. [Formula: see text] and [Formula: see text] provide a crucial link between theoretical predictions and empirical observations. Through rigorous mathematical analysis and theoretical modeling, we investigate the implications of this extended gravitational theory on cosmic evolution and the structure of spacetime. Our findings shed light on the interplay between geometry, matter and gravitational dynamics in multidimensional space, offering new insights into the nature of gravity and cosmological phenomenon.
R. K. MISHRA, , NAVYA JAIN, and
Editura Academiei Romane
This study explore the dynamics of cosmic expansion through a detailed exploration of a novel form of the deceleration parameter, denoted as q = α(t 2−1) t 2+1 , within the framework of f(R,T) gravity theory. This study employs both observational and theoretical approaches to unveil the intricate interplay of cosmic forces and phenomena that have a profound influence on the ever-evolving universe. The primary objective of this investigation is to gain a deeper understanding of the expanding dynamics, particularly the transition from deceleration to acceleration. The findings of this paper shed light on the presence of a phase transition and an initial singularity, while remaining consistent with the ΛCDM model. Moreover, this study serves as a foundation for further exploration within the f(R,T) gravity framework, providing fresh insights into the cosmos and offering a profound comprehension of the universe’s dynamic evolution.
R. K. Mishra and Navya Jain
Springer Science and Business Media LLC
R. K. Mishra and Heena Dua
Springer Science and Business Media LLC
Navya Jain, Heena Dua, and R K Mishra
IOP Publishing
Abstract The present study deals with the investigation of the Friedmann-Lemaitre-Robertson-Walker models (often FLRW-models) with time varying G and ∧ in the framework of General theory of Relativity. The Einstein field equations have been solved by considering the time-varying deceleration parameter q(t) and Scale factor α ( t ) = e β t + ( sinh β t ) 1 m , where m and β are arbitrary constants. We have analysed the value of m, which will generate a transition for universe from early decelerating phase to recent acceleration phase. The physical and graphic behaviour have also been planned to study in this communication.
Rahul Sharma, Avtar Chand, and R K Mishra
IOP Publishing
Abstract In this communication, we have explored spatially homogeneous, anisotropic Bianchi-II space-time in f(R, T) theory of gravity. Here, we have obtained an explicit solution of the field equations of f(R, T) theory with time dependent fractional linear varying deceleration parameter (FLVDP) i.e. q(t). The accelerating expanding nature of the cosmos has been also discussed under the suitable assumption q ( t ) = α ( 1 − t ) 1 + t , here α > 0. It is observed that the universe was originated from a singularity in the past and is expanding at an accelerating rate. The FLVDP depicts a transitional phase i.e., early deceleration to the current accelerating phase.
Heena Dua and R. K. Mishra
AIP Publishing
This study investigates Bianchi type-I cosmological model in Brans-Dicke theory of gravity. The present accelerated expansion of the universe has been described using bilinear varying deceleration parameter, q=γ−ηt1+ηt; with γ and η as positive constants (Mishra et al. in Astrophys. Space Sci. 361:259, 2016). We obtain an exact solution of the field equations in modified gravity. The derived cosmological model starts evolving from an initial Big-Bang singularity and is expanding continuously with the passage of cosmic time. Some physical and geometrical properties of the universe are discussed. The evolution of energy conditions and statefinder pair is also examined. The findings are observed to be in good agreement with the recent observational data reported in literature.
R. K. Mishra and Heena Dua
Springer Science and Business Media LLC
R. K. Mishra and Heena Dua
Springer Science and Business Media LLC
R. K. Mishra and Heena Dua
Springer Science and Business Media LLC
R. K. Mishra and Avtar Chand
Springer Science and Business Media LLC
R. K. Mishra and Heena Dua
Springer Science and Business Media LLC
R. K. Mishra, Heena Dua, and Avtar Chand
Springer Science and Business Media LLC
R. K. Mishra and Avtar Chand
Springer Science and Business Media LLC
R. K. Mishra and Avtar Chand
Springer Science and Business Media LLC
Avtar Chand, R. K. Mishra, and Anirudh Pradhan
Springer Science and Business Media LLC
R. K. Mishra, Avtar Chand, and Anirudh Pradhan
Springer Science and Business Media LLC
Avtar Chand and R. K. Mishra
AIP Publishing LLC
In this paper we have investigated the Bianchi type-II cosmological model with variable parameters in the frame work of modified f(R, T) gravity theory as suggested by Harko et al. (Phys. Rev. D, 84:024020). As we know that the effect of space-time curvature upon phase transition is an expanding universe. In this communication we have constructed a cosmological model of the universe by taking suitable assumptions along with string in presence of magnetic field. It is to be noted that our procedure for solving the field equations is different from other authors as we have consider the time dependent deceleration parameter (DP), it means that the universe which was decelerating in the past is accelerating at present time. We found that the universe is decelerating for q > 0 and accelerating for −1 ≤ q < 0, which shown signature flipping.