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Full-Text Articles in Physical Sciences and Mathematics
A 3+1 Decomposition Of The Minimal Standard-Model Extension Gravitational Sector, Nils A. Nilsson, Kellie O'Neal-Ault, Quentin G. Bailey
A 3+1 Decomposition Of The Minimal Standard-Model Extension Gravitational Sector, Nils A. Nilsson, Kellie O'Neal-Ault, Quentin G. Bailey
Publications
The 3+1 (ADM) formulation of General Relativity is used in, for example, canonical quantum gravity and numerical relativity. Here we present a 3+1 decomposition of the minimal Standard-Model Extension gravity Lagrangian. By choosing the leaves of foliation to lie along a timelike vector field we write the theory in a form which will allow for comparison and matching to other gravity models.
Recent Developments In Spacetime-Symmetry Tests In Gravity, Q. G. Bailey
Recent Developments In Spacetime-Symmetry Tests In Gravity, Q. G. Bailey
Publications
Motivated by potentially detectable but minuscule signatures from Planckscale or other new physics, there has been a substantial increase in tests of spacetime symmetry in gravity in recent years. Some novel hypothetical effects that break local Lorentz symmetry and CPT symmetry in gravitational experiments as well as solar system and astrophysical observations have been studied in recent works. Much of this work uses the effective field theory framework, the Standard-Model Extension (SME), that includes gravitational couplings. In other cases, the parameters in specific hypothetical models of Lorentz violation in gravity have been tested.
Testing The Gravitational Weak Equivalence Principle In The Standard-Model Extension With Binary Pulsars, Lijing Shao, Quentin G. Bailey
Testing The Gravitational Weak Equivalence Principle In The Standard-Model Extension With Binary Pulsars, Lijing Shao, Quentin G. Bailey
Publications
The standard model extension provides a framework to systematically investigate possible violation of the Lorentz symmetry. Concerning gravity, the linearized version was extensively examined. We here cast the first set of experimental bounds on the nonlinear terms in the field equation from the anisotropic cubic curvature couplings. These terms introduce body-dependent accelerations for self-gravitating objects, thus violating the gravitational weak equivalence principle (GWEP). Novel phenomena, which are absent in the linearized gravity, remain experimentally unexplored. We constrain them with precise binary-orbit measurements from pulsar timing, wherein the high density and large compactness of neutron stars are crucial for the test. …