Zobrazeno 1 - 10
of 211
pro vyhledávání: '"Sanyal, Abhik Kumar"'
Teleparallel gravity theories were proposed as alternatives to the dark energy and modified theories of gravity. However, both the metric and symmetric teleparallel gravity theories have been found to have serious pathologies, such as coupling issues
Externí odkaz:
http://arxiv.org/abs/2407.09586
Publikováno v:
Universe 2024, 10, 44
A viable radiation dominated era in the early universe is best described by the standard (FLRW) model of cosmology. In this short review, we demonstrate reconstruction of the forms of F(R) in the modified theory of gravity and the metric compatible F
Externí odkaz:
http://arxiv.org/abs/2401.11226
Publikováno v:
International Journal of Geometric Methods in Modern Physics (2023) 2350213 (48 pages), World Scientific Publishing Company
In the last decade Planck PR4 data together with ground-based experimental data such as, BK18, BAO and CMB lensing, tightened constraint of the tensor to scalar ratio, starting form $r < 0.14$ to $r < 0.032$, while the spectral index lies within the
Externí odkaz:
http://arxiv.org/abs/2308.11770
Unlike F(R) gravity, pure metric F(T) gravity in the vacuum dominated era, ends up with an imaginary action and is therefore not feasible. This eerie situation may only be circumvented by associating a scalar field, which can also drive inflation in
Externí odkaz:
http://arxiv.org/abs/2304.04180
Autor:
Saha, Dalia, Sanyal, Abhik Kumar
Publikováno v:
Universe 2023, 9, 48 (2023)
Ostrogradsky's, Dirac's and Horowitz's techniques of higher order theories of gravity produce identical phase-space structures. The problem is manifested in the case of Gauss-Bonnet-dilatonic coupled action in the presence of higher-order term, in wh
Externí odkaz:
http://arxiv.org/abs/2301.05710
General theory of relativity can be equivalently formulated on a flat spacetime that associates with a torsion-free affine connection of non-vanishing non-metricity scalar $Q$. In this work, we present an extension of this, the $f(Q)$ theory of gravi
Externí odkaz:
http://arxiv.org/abs/2209.12120
Publikováno v:
International Journal of Modern Physics D, (2022) 2250083 (14 pages) (2022)
As in the case of Lanczos-Lovelock gravity, the main advantage of F(T) gravity is said to be that it leads to second order field equations, while F(R) gravity theory leads to fourth order equations. We show that it is rather a disadvantage, since it
Externí odkaz:
http://arxiv.org/abs/2201.08390
Autor:
Saha, Dalia, Sanyal, Abhik Kumar
Publikováno v:
Indian Journal of Theoretical Physics, Volume 68, Nos. 3,4, pages 53-98 (2020), ISSN: 0019-5693
In the recent years, a host of modified gravity models have been proposed as alternatives to the dark energy. A quantum theory of gravity also requires to modify `General Theory of Relativity'. In the present article, we consider five different modif
Externí odkaz:
http://arxiv.org/abs/2201.02473
Publikováno v:
Euro.Phys.J.Plus, 2021
We study early universe with a particular form of F(T) Telleparallel gravity theory, in which inflation is driven by a scalar field. To ensure slow rollover, two different potentials are chosen in a manner, such that they remain almost flat for large
Externí odkaz:
http://arxiv.org/abs/2112.09609
Publikováno v:
Nuclear Physics B 973 (2021) 115570
A viable quantum theory does not allow curvature invariant terms of different higher orders to be accommodated in the gravitational action. We show that there is indeed a conflict between the curvature squared and Gauss-Bonnet squared terms from the
Externí odkaz:
http://arxiv.org/abs/2106.06740