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Articles 1 - 14 of 14
Full-Text Articles in Physics
Bps Brane Cosmology In N=2 Supergravity, Moataz Emam
Bps Brane Cosmology In N=2 Supergravity, Moataz Emam
Moataz Emam
We study the embedding of flat BPS 3-branes in five dimensional N=2 supergravity theory. We derive the branes' dynamical equations as well as general expressions for the hypermultiplet fields then focus on a single brane and study its time evolution. It is shown that the brane's Hubble parameter correlates with the moduli of the underlying manifold's complex structure. For certain particular solutions, the moduli seem to exhibit an instability; being large valued at early times then rapidly decaying to either zero or some convergent constant value. The possibility of extending these results to the cosmology of our universe is implied …
Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos
Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos
Charles G. Torre
Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and electromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equations are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Geometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and formulas for constructing the scalar field from …
A Solution In Weyl Gravity With Planar Symmetry, James Thomas Wheeler
A Solution In Weyl Gravity With Planar Symmetry, James Thomas Wheeler
James Thomas Wheeler
We solve the Bach equation for Weyl gravity for the case of a static metric with planar symmetry. The solution is not conformal to the solution to the corresponding Einstein equation.
The Spacetime Co-Torsion In Torsion-Free Biconformal Spaces, James Thomas Wheeler
The Spacetime Co-Torsion In Torsion-Free Biconformal Spaces, James Thomas Wheeler
James Thomas Wheeler
In preceding studies, [TR Gamma minus, TR Gamma plus] we showed that the solution for the connection of flat biconformal space also solves the curved space field equations for the torsion and co-torsion. We continued this investigation with an attempt to solve the full set of torsion and co-torsion field equations, with only the assumption of vanishing torsion and the known form of the metric. We successfully reduced the torsion equations to a single equation. Here, we reduce that equation to its essential degrees of freedom. We find that the spacetime co-torsion is entirely determined by the scale vector and …
Variation Of The Weyl Action, James Thomas Wheeler
Variation Of The Weyl Action, James Thomas Wheeler
James Thomas Wheeler
We show how to vary the fourth order Weyl gravity action to derive the Bach equation.
Lorentz Violation With An Antisymmetric Tensor, Brett Altschul, Quentin G. Bailey, V. Alan Kostelecky
Lorentz Violation With An Antisymmetric Tensor, Brett Altschul, Quentin G. Bailey, V. Alan Kostelecky
Quentin Bailey
Field theories with spontaneous Lorentz violation involving an antisymmetric 2-tensor are studied. A general action including nonminimal gravitational couplings is constructed, and features of the Nambu- Goldstone and massive modes are discussed. Minimal models in Minkowski spacetime exhibit dualities with Lorentz-violating vector and scalar theories. The post-Newtonian expansion for nonminimal models in Riemann spacetime involves qualitatively new features, including the absence of an isotropic limit. Certain interactions producing stable Lorentz-violating theories in Minkowski spacetime solve the renormalization-group equations in the tadpole approximation.
Lorentz-Violating Gravitoelectromagnetism, Quentin G. Bailey
Lorentz-Violating Gravitoelectromagnetism, Quentin G. Bailey
Quentin Bailey
The well-known analogy between a special limit of general relativity and electromagnetism is explored in the context of the Lorentz-violating standard-model extension. An analogy is developed for the minimal standard-model extension that connects a limit of the CPT-even component of the electromagnetic sector to the gravitational sector. We show that components of the post-Newtonian metric can be directly obtained from solutions to the electromagnetic sector. The method is illustrated with specific examples including static and rotating sources. Some unconventional effects that arise for Lorentz-violating electrostatics and magnetostatics have an analog in Lorentz-violating post-Newtonian gravity. In particular, we show that even …
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin
Quentin Bailey
Generic violations of Lorentz symmetry can be described by an effective field theory framework that contains both general relativity and the Standard Model of particle physics called the Standard-Model extension (SME). We obtain new constraints on the gravitational sector of the SME using recently published final results from Gravity Probe B. These include for the first time an upper limit at the 10_3 level on the time-time component of the new tensor field responsible for inducing local Lorentz violation in the theory, and an independent limit at the 10_7 level on a combination of components of this tensor field.
Time-Delay And Doppler Tests Of The Lorentz Symmetry Of Gravity, Quentin G. Bailey
Time-Delay And Doppler Tests Of The Lorentz Symmetry Of Gravity, Quentin G. Bailey
Quentin Bailey
Modifications to the classic time-delay effect and Doppler shift in general relativity (GR) are studied in the context of the Lorentz-violating standard-model extension (SME). We derive the leading Lorentz- violating corrections to the time-delay and Doppler shift signals, for a light ray passing near a massive body. It is demonstrated that anisotropic coefficients for Lorentz violation control a time-dependent behavior of these signals that is qualitatively different from the conventional case in GR. Estimates of sensitivities to gravity-sector coefficients in the SME are given for current and future experiments, including the recent Cassini solar conjunction experiment.
Catching Relativity Violations With Atoms, Quentin G. Bailey
Catching Relativity Violations With Atoms, Quentin G. Bailey
Quentin Bailey
A Viewpoint on: Atom interferometry tests of local Lorentz invariance in gravity and electrodynamics Keng-Yeow Chung, Sheng-wey Chiow, Sven Herrmann, Steven Chu and Holger Müller Phys. Rev. D 80, 016002 (2009) – Published July 6, 2009.
Light-Bending Tests Of Lorentz Invariance, Quentin G. Bailey, Rhondale Tso
Light-Bending Tests Of Lorentz Invariance, Quentin G. Bailey, Rhondale Tso
Quentin Bailey
Classical light-bending is investigated for weak gravitational fields in the presence of hypothetical local Lorentz violation. Using an effective field theory framework that describes general deviations from local Lorentz invariance, we derive a modified deflection angle for light passing near a massive body. The results include anisotropic effects not present for spherical sources in General Relativity as well as Weak Equivalence Principle violation. We develop an expression for the relative deflection of two distant stars that can be used to analyze data in past and future solar-system observations. The measurement sensitivities of such tests to coefficients for Lorentz violation are …
Torsion Free Biconformal Spaces: Reducing The Torsion Field Equations, James Thomas Wheeler
Torsion Free Biconformal Spaces: Reducing The Torsion Field Equations, James Thomas Wheeler
James Thomas Wheeler
Our goal is to solve the full set of torsion and co-torsion field equations of Euclidean biconformal space, with only the assumption of vanishing torsion. Here we begin by resolving the involution constraints, symmetry conditions and torsion field equation into a single equation for further study.
The Spatial Distribution Of Electric Field Intensity When The Motion Of Electric Charge In Absolute Space, Vildyan Yanbikov
The Spatial Distribution Of Electric Field Intensity When The Motion Of Electric Charge In Absolute Space, Vildyan Yanbikov
Vildyan Yanbikov
При движении электрического или гравитационного заряда в абсолютном пространстве. Поля, создаваемого этими частицами, будет иметь другое распределение в пространстве. В сравнении со стационарным бесплатно. При движении заряда поля деформаций.
The Spatial Distribution Of Electric Field Intensity When The Motion Of Electric Charge In Absolute Space, Vildyan Yanbikov
The Spatial Distribution Of Electric Field Intensity When The Motion Of Electric Charge In Absolute Space, Vildyan Yanbikov
Vildyan Yanbikov
When driving an electric or gravitational charge in absolute space. Field created by these particles will have a different distribution in space. In comparison with by a stationary charge. When the charge motion of the deformation field.