scholarly journals Disformal Transformations in Scalar–Torsion Gravity

Universe ◽  
2019 ◽  
Vol 5 (7) ◽  
pp. 167 ◽  
Author(s):  
Manuel Hohmann
Keyword(s):  
Gravitational Interaction ◽  
Teleparallel Gravity ◽  
Generic Class ◽  
Flat Metric ◽  
Scalar Extensions

We study disformal transformations in the context of scalar extensions to teleparallel gravity, in which the gravitational interaction is mediated by the torsion of a flat, metric compatible connection. We find a generic class of scalar–torsion actions which is invariant under disformal transformations, and which possesses different invariant subclasses. For the most simple of these subclasses we explicitly derive all terms that may appear in the action. We propose to study actions from this class as possible teleparallel analogues of healthy beyond Horndeski theories.

scholarly journals A duality between curvature and torsion

2018 ◽  
Vol 27 (14) ◽  
pp. 1847008 ◽  
Author(s):  
Swanand Khanapurkar ◽  
Tejinder P. Singh
Keyword(s):  
Scale Effects ◽  
Gravitational Interaction ◽  
Large Mass ◽  
Small Mass ◽  
Teleparallel Gravity ◽  
Einstein Equations ◽  
Small Scale ◽  
Underlying Theory ◽  
Newman Black Hole ◽  
Curvature And Torsion

Compton wavelength and Schwarzschild radius are considered here as limiting cases of a unified length scale. Using this length, it is shown that the Dirac equation and the Einstein equations for a point mass are limiting cases of an underlying theory which includes torsion. We show that in this underlying theory, the gravitational interaction between small masses is weaker than in Newtonian gravity. We explain as to why the Kerr–Newman black hole and the electron both have the same nonclassical gyromagnetic ratio. We propose a duality between curvature and torsion and show that general relativity and teleparallel gravity are respectively the large mass and small mass limit of the ECSK theory. We demonstrate that small scale effects of torsion can be tested with current technology.

scholarly journals GRAVITATION AND DUALITY SYMMETRY

2005 ◽  
Vol 14 (09) ◽  
pp. 1635-1648 ◽  
Author(s):  
V. C. DE ANDRADE ◽  
A. L. BARBOSA ◽  
J. G. PEREIRA
Keyword(s):  
General Relativity ◽  
Gravitational Interaction ◽  
Teleparallel Gravity ◽  
Dual Operator ◽  
Duality Symmetry ◽  
Basic Conclusion ◽  
Tensor Part

By generalizing the Hodge dual operator to the case of soldered bundles, and working in the context of the teleparallel equivalent of general relativity, an analysis of the duality symmetry in gravitation is performed. Although the basic conclusion is that, at least in the general case, gravitation is not dual symmetric, there is a particular theory in which this symmetry shows up. It is a self dual (or anti-self dual) teleparallel gravity in which, due to the fact that it does not contribute to the interaction of fermions with gravitation, the purely tensor part of torsion is assumed to vanish. The ensuing fermionic gravitational interaction is found to be chiral. Since duality is intimately related to renormalizability, this theory may eventually be more amenable to renormalization than teleparallel gravity or general relativity.

scholarly journals Traversable wormhole solutions with non-exotic fluid in framework of f(Q) gravity

2021 ◽  
Author(s):  
Umesh Kumar Sharma ◽  
Shweta ◽  
Ambuj Kumar Mishra
Keyword(s):  
Shape Function ◽  
Gravitational Interaction ◽  
Teleparallel Gravity ◽  
Energy Conditions ◽  
Throat Radius ◽  
Traversable Wormholes ◽  
Normal Matter ◽  
Modified Gravity Theories ◽  
Existence And Stability ◽  
Nonlinear Form

The presence of exotic matter for the existence of the wormhole geometry has been an unavoidable problem in GR. In recent studies, researchers have tried to deal with this issue using modified gravity theories where the WH geometry is explained by the extra curvature terms and NEC’s are not violated signifying the standard matter in the WH geometry. In this paper, we investigate the solutions of traversable wormholes with normal matter in the throat within the framework of symmetric teleparallel gravity [Formula: see text], where [Formula: see text] is the non-metricity scalar that defines the gravitational interaction. We analyze the wormhole geometries for three forms of function [Formula: see text]. First is the linear form [Formula: see text], second a nonlinear form [Formula: see text] and third one a more general quadratic form [Formula: see text] with [Formula: see text], [Formula: see text] and [Formula: see text] being the constants. For all the three cases, the shape function is taken as [Formula: see text] where [Formula: see text] is the throat radius. A special variable redshift function is considered for the discussion. All the energy conditions are then examined for the existence and stability of the wormhole geometry.

scholarly journals Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 358
Author(s):  
Roberto Casadio ◽  
Andrea Giusti
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Physics ◽  
Gravitational Interaction ◽  
Newtonian Gravity ◽  
Cosmological Constant Problem ◽  
Newtonian Cosmology ◽  
Natural Solution ◽  
The Impact

Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmology can lead to a natural solution to the cosmological constant problem.

scholarly journals Fractional Integral Inequalities for Exponentially Nonconvex Functions and Their Applications

2021 ◽  
Vol 5 (3) ◽  
pp. 80
Author(s):  
Hari Mohan Srivastava ◽  
Artion Kashuri ◽  
Pshtiwan Othman Mohammed ◽  
Dumitru Baleanu ◽  
Y. S. Hamed
Keyword(s):  
Integral Inequalities ◽  
Fractional Integrals ◽  
Auxiliary Result ◽  
Wright Function ◽  
Nonconvex Functions ◽  
Special Cases ◽  
Type Integral ◽  
Generic Class ◽  
Two Parameters ◽  
Class Of Functions

In this paper, the authors define a new generic class of functions involving a certain modified Fox–Wright function. A useful identity using fractional integrals and this modified Fox–Wright function with two parameters is also found. Applying this as an auxiliary result, we establish some Hermite–Hadamard-type integral inequalities by using the above-mentioned class of functions. Some special cases are derived with relevant details. Moreover, in order to show the efficiency of our main results, an application for error estimation is obtained as well.

scholarly journals Galaxy spin direction distribution in HST and SDSS show similar large-scale asymmetry

2020 ◽  
Vol 37 ◽  
Author(s):  
Lior Shamir
Keyword(s):  
Large Scale ◽  
Spiral Galaxies ◽  
Hubble Space Telescope ◽  
Gravitational Interaction ◽  
Large Data ◽  
Sloan Digital Sky Survey ◽  
Data Sets ◽  
Dipole Axis ◽  
Data Set ◽  
The Asymmetry

Abstract Several recent observations using large data sets of galaxies showed non-random distribution of the spin directions of spiral galaxies, even when the galaxies are too far from each other to have gravitational interaction. Here, a data set of $\sim8.7\cdot10^3$ spiral galaxies imaged by Hubble Space Telescope (HST) is used to test and profile a possible asymmetry between galaxy spin directions. The asymmetry between galaxies with opposite spin directions is compared to the asymmetry of galaxies from the Sloan Digital Sky Survey. The two data sets contain different galaxies at different redshift ranges, and each data set was annotated using a different annotation method. The results show that both data sets show a similar asymmetry in the COSMOS field, which is covered by both telescopes. Fitting the asymmetry of the galaxies to cosine dependence shows a dipole axis with probabilities of $\sim2.8\sigma$ and $\sim7.38\sigma$ in HST and SDSS, respectively. The most likely dipole axis identified in the HST galaxies is at $(\alpha=78^{\rm o},\delta=47^{\rm o})$ and is well within the $1\sigma$ error range compared to the location of the most likely dipole axis in the SDSS galaxies with $z>0.15$ , identified at $(\alpha=71^{\rm o},\delta=61^{\rm o})$ .

scholarly journals Teleparallel gravity with non-minimally coupled f-essence via Noether symmetry approach

2021 ◽  
Vol 1730 (1) ◽  
pp. 012022
Author(s):  
Kairat Myrzakulov ◽  
Duman Kenzhalin ◽  
Nurgissa Myrzakulov
Keyword(s):  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Symmetry Approach

scholarly journals Gravitational Interaction in the Chimney Lattice Universe

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 101
Author(s):  
Maxim Eingorn ◽  
Andrew McLaughlin ◽  
Ezgi Canay ◽  
Maksym Brilenkov ◽  
Alexander Zhuk
Keyword(s):  
Helmholtz Equation ◽  
Gravitational Potential ◽  
Fourier Expansion ◽  
Gravitational Interaction ◽  
Alternative Solution ◽  
The Third ◽  
Present Universe ◽  
Delta Functions ◽  
Yukawa Potentials ◽  
The Universe

We investigate the influence of the chimney topology T×T×R of the Universe on the gravitational potential and force that are generated by point-like massive bodies. We obtain three distinct expressions for the solutions. One follows from Fourier expansion of delta functions into series using periodicity in two toroidal dimensions. The second one is the summation of solutions of the Helmholtz equation, for a source mass and its infinitely many images, which are in the form of Yukawa potentials. The third alternative solution for the potential is formulated via the Ewald sums method applied to Yukawa-type potentials. We show that, for the present Universe, the formulas involving plain summation of Yukawa potentials are preferable for computational purposes, as they require a smaller number of terms in the series to reach adequate precision.

scholarly journals Wormhole Solutions in Symmetric Teleparallel Gravity with Noncommutative Geometry

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1260
Author(s):  
Zinnat Hassan ◽  
Ghulam Mustafa ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Linear Model ◽  
Noncommutative Geometry ◽  
Teleparallel Gravity ◽  
Exponential Model ◽  
Model Parameter ◽  
Exponential Models ◽  
Feasible Solutions ◽  
The Stability ◽  
Tov Equation

This article describes the study of wormhole solutions in f(Q) gravity with noncommutative geometry. Here, we considered two different f(Q) models—a linear model f(Q)=αQ and an exponential model f(Q)=Q−α1−e−Q, where Q is the non-metricity and α is the model parameter. In addition, we discussed the existence of wormhole solutions with the help of the Gaussian and Lorentzian distributions of these linear and exponential models. We investigated the feasible solutions and graphically analyzed the different properties of these models by taking appropriate values for the parameter. Moreover, we used the Tolman–Oppenheimer–Volkov (TOV) equation to check the stability of the wormhole solutions that we obtained. Hence, we found that the wormhole solutions obtained with our models are physically capable and stable.

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