scholarly journals First-order formalism for thick branes in modified gravity with Lagrange multiplier

2020 ◽  
Vol 129 (1) ◽  
pp. 11004 ◽  
Author(s):  
D. Bazeia ◽  
D. A. Ferreira ◽  
D. C. Moreira
2011 ◽  
Vol 28 (3) ◽  
pp. 035010 ◽  
Author(s):  
Yi-Fu Cai ◽  
Emmanuel N Saridakis

2020 ◽  
Vol 15 (10) ◽  
Author(s):  
Edward J. Haug

Abstract Four formulations of nonholonomic mechanical system dynamics, with both holonomic and differential constraints, are presented and shown to be well posed; i.e., solutions exist, are unique, and depend continuously on problem data. They are (1) the d'Alembert variational formulation, (2) a broadly applicable manifold theoretic extension of Maggi's equations that is a system of first-order ordinary differential equations (ODE), (3) Lagrange multiplier-based index 3 differential-algebraic equations (index 3 DAE), and (4) Lagrange multiplier-based index 0 differential-algebraic equations (index 0 DAE). The ODE formulation is shown to be well posed, as a direct consequence of the theory of ODE. The variational formulation is shown to be equivalent to the ODE formulation, hence also well posed. Finally, the index 3 DAE and index 0 DAE formulations are shown to be equivalent to the variational and ODE formulations, hence also well posed. These results fill a void in the literature and provide a theoretical foundation for nonholonomic mechanical system dynamics that is comparable to the theory of ODE.


2021 ◽  
Vol 136 (3) ◽  
Author(s):  
Dionisio Bazeia ◽  
D. A. Ferreira ◽  
Francisco S. N. Lobo ◽  
João Luís Rosa

Author(s):  
Brett D Altschul ◽  
J Roberto S Nascimento ◽  
A Yu Petrov ◽  
P. J. Porfı́rio

Abstract G\"{o}del-type metrics that are homogeneous in both space and time remain, like the Schwarzschild metric, consistent within Chern-Simons modified gravity; this is true in both the non-dynamical and dynamical frameworks, each of which involves an additional pseudoscalar field coupled to the Pontryagin density. In this paper, we consider stationary first-order perturbations to these metrics in the non-dynamical framework. Under certain assumptions we find analytical solutions to the perturbed field equations. The solutions of the first-order field equations break the translational and cylindrical symmetries of the unperturbed metrics. The effective potential controlling planar geodesic orbits is also affected by the perturbation parameter, which changes the equilibrium radii for the orbits of both massive particles and massless photons.


2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040019
Author(s):  
V. Dzhunushaliev ◽  
V. Folomeev ◽  
G. Nurtayeva ◽  
A. Serikbolova ◽  
S.-W. Kim

Vacuum solutions describing thick branes with codimension 1 within higher-dimensional [Formula: see text] modified gravity are constructed. The dependence of these solutions on the parameters determining the solutions is studied numerically.


2021 ◽  
Vol 81 (9) ◽  
Author(s):  
J. W. Moffat ◽  
V. T. Toth

AbstractWe investigate the contributions of the Friedmann–Lemaître–Robertson–Walker metric of the standard cosmology as an asymptotic boundary condition on the first-order approximation of the gravitational field in Moffat’s theory of modified gravity (MOG). We also consider contributions due to the fact that the MOG theory does not satisfy the shell theorem or Birkhoff’s theorem, resulting in what is known as the “external field effect” (EFE). We show that while both these effects add small contributions to the radial acceleration law, the result is orders of magnitude smaller than the radial acceleration in spiral galaxies.


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