String corrections to the gravitational equations of motion and inflation

Gravitational equations of motion in modified theories of gravity have oscillating solutions, both in the early and in the present day universe. Particle production by such oscillations is analyzed and possible observational consequences are considered. This phenomenon has impact on energy spectrum of cosmic rays and abundance of dark matter particles.

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Testing alternate gravitational theories

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309990354 ◽

2009 ◽

Vol 5 (S261) ◽

pp. 179-182 ◽

Cited By ~ 6

Author(s):

E. M. Standish

Keyword(s):

Equations Of Motion ◽

The Sun ◽

Constant Acceleration ◽

Gravitational Theories ◽

Pioneer Anomaly ◽

The Future ◽

Gravitational Equations

AbstractThe planetary ephemerides are used to examine different suggested forms of the gravitational equations of motion which could possibly cause the observed Pioneer Anomaly. It is shown that most of the forms would be unacceptable, including that generally assumed – a constant acceleration directed toward the Sun. The tests show that three other forms could not exist within 10 au's of the Sun. Only one suggested form would be compatible with the Pioneer Anomaly affecting Saturn or any other more inward planet. Additional planetary observations in the future may possibly eliminate this form also.

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Cosmological viscous fluid models describing infinite time singularities in f(T) gravity

The European Physical Journal C ◽

10.1140/epjc/s10052-020-8252-8 ◽

2020 ◽

Vol 80 (9) ◽

Author(s):

R. D. Boko ◽

M. J. S. Houndjo

Keyword(s):

Dark Energy ◽

Equations Of Motion ◽

State Parameter ◽

Infinite Time ◽

Constant Deceleration Parameter ◽

Two Fluids ◽

Viscosity Models ◽

Time Singularities ◽

Analytic Expressions ◽

Gravitational Equations

AbstractIn this paper we explore the state parameter behaviour of the interacting viscous dark energy in f(T) gravity. Using constant deceleration parameter we investigate the cosmological implications of the viscosity and interaction between the dark components (energy and matter) in terms of Redshift. So doing, the viscosity and the interaction between the two fluids are parameterized by constants $$\delta $$ δ and $$\xi $$ ξ respectively. In the later part of the paper, we explore some bulk viscosity models describing Little Rip and Pseudo Rip future singularities within f(T) modified gravity. We obtain gravitational equations of motion for viscous dark energy coupled with dark matter. Solving these equations, we found analytic expressions for characteristic properties of these cosmological models.

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Extended corner symmetry, charge bracket and Einstein’s equations

Journal of High Energy Physics ◽

10.1007/jhep09(2021)083 ◽

2021 ◽

Vol 2021 (9) ◽

Author(s):

Laurent Freidel ◽

Roberto Oliveri ◽

Daniele Pranzetti ◽

Simone Speziale

Keyword(s):

Vector Field ◽

Phase Space ◽

Equations Of Motion ◽

Symmetry Algebra ◽

Canonical Representation ◽

Space Formalism ◽

Surface Translation ◽

The One ◽

A Charge ◽

Gravitational Equations

Abstract We develop the covariant phase space formalism allowing for non-vanishing flux, anomalies, and field dependence in the vector field generators. We construct a charge bracket that generalizes the one introduced by Barnich and Troessaert and includes contributions from the Lagrangian and its anomaly. This bracket is uniquely determined by the choice of Lagrangian representative of the theory. We then extend the notion of corner symmetry algebra to include the surface translation symmetries and prove that the charge bracket provides a canonical representation of the extended corner symmetry algebra. This representation property is shown to be equivalent to the projection of the gravitational equations of motion on the corner, providing us with an encoding of the bulk dynamics in a locally holographic manner.

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Spontaneous and gravitational baryogenesis

International Journal of Modern Physics A ◽

10.1142/s0217751x18440232 ◽

2018 ◽

Vol 33 (31) ◽

pp. 1844023 ◽

Cited By ~ 1

Author(s):

E. V. Arbuzova

Keyword(s):

Equations Of Motion ◽

Curvature Scalar ◽

Strong Instability ◽

Standard Cosmology ◽

Dependent Term ◽

Gravitational Equations

Some problems of spontaneous and gravitational baryogenesis are discussed. Gravity modification due to the curvature-dependent term in gravitational baryogenesis scenario is considered. It is shown that the interaction of baryonic fields with the curvature scalar leads to strong instability of the gravitational equations of motion and as a result to noticeable distortion of the standard cosmology.

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Radiation and Gravitational Equations of Motion

Canadian Journal of Mathematics ◽

10.4153/cjm-1951-024-8 ◽

1951 ◽

Vol 3 ◽

pp. 195-207 ◽

Cited By ~ 23

Author(s):

L. Infeld ◽

A. E. Scheidegger

Keyword(s):

General Relativity ◽

Equations Of Motion ◽

Classical Field ◽

Relativity Theory ◽

Field Theories ◽

Field Equations ◽

General Relativity Theory ◽

Principle Of Superposition ◽

Classical Field Theories ◽

Gravitational Equations

Among the classical field theories, general relativity theory occupies a somewhat peculiar place. Unlike those of most other field theories, the field equations in relativity theory are non-linear. This implies that many facts, well known in linear theories, have no analogues in general relativity theory, and conversely. The equations of motion of the sources of the gravitational field are contained in the field equations, a fact which does not apply for the motion of an electron in the electromagnetic field. Conversely, it is difficult to define the notion of a wave (familiar in electrodynamics) in relativity theory; for, the linear principle of superposition is crucial for the existence of waves (at least in the sense that the notion of a wave is normally used).

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The motion of a lunar orbiter

Symposium - International Astronomical Union ◽

10.1017/s0074180900105686 ◽

1966 ◽

Vol 25 ◽

pp. 373

Author(s):

Y. Kozai

Keyword(s):

Degrees Of Freedom ◽

Dimensional Space ◽

Artificial Satellite ◽

Equations Of Motion ◽

Triaxial Ellipsoid ◽

The Moon ◽

Secular Motion ◽

The Earth ◽

Close Satellite ◽

The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

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