Related papers: Constraints on relativity violations from gamma-ra…
In quantum theory of gravity, we expect the Lorentz Invariance Violation (LIV) and the modification of the dispersion relation between energy and momentum for photons. The effect of the energy-dependent velocity due to the modified…
I discuss some theoretical ideas concerning the representation of quantum gravity as a Lorentz-symmetry-violating `medium' with non-trivial optical properties, which include a refractive index in `vacuo' and stochastic effects associated…
We account for particle emission and gravitational radiation from cosmic string loops to determine their effect on the loop distribution and observational signatures of strings. The effect of particle emission is that the number density of…
Out of conviction or expediency, some current research programs take for granted that "PCT violation implies violation of Lorentz invariance". We point out that this claim is still on somewhat shaky ground. In fact, for many years there has…
The formulation and some experimental implications of a general Lorentz-violating extension of the standard model are reviewed. The theory incorporates both CPT-preserving and CPT-breaking terms. It is otherwise a conventional quantum field…
In some quantum theories of gravity, deviations from the laws of relativity could be comparatively large while escaping detection to date. In the neutrino sector, precision experiments with beta decay yield new and improved constraints on…
Motivated by ideas from quantum gravity, Lorentz invariance has undergone many stringent tests over the past decade and passed every one. Since there is no conclusive reason from quantum gravity that the symmetry \textit{must} be violated…
Lorentz Invariance Violation (LIV) may be a good observational window on Quantum Gravity physics. Within last few years, all major Gamma-ray experiments have published results from the search for LIV with variable astrophysical sources:…
Much research has been done in the latter years on the subject of Lorentz violation induced by Quantum Gravity effects. On the theoretical side it has been shown that both Loop Quantum Gravity and String Theory predict that Lorentz…
We review the basics of the two most widely used approaches to Lorentz violation - the Stardard Model Extension and Noncommutative Field Theory - and discuss in some detail the example of the modified spectrum of the synchrotron radiation.…
Despite the tremendous empirical success of equivalence principle, there are several theoretical motivations for existence of a preferred reference frame (or aether) in a consistent theory of quantum gravity. However, if quantum gravity had…
If there is Lorentz symmetry violation in the $t$ quark sector of the standard model, changes to particles' dispersion relations might allow for the existence of stable top-flavored hadrons. Observations of the survival of high-energy…
Trying to combine standard quantum field theories with gravity leads to a breakdown of the usual structure of space-time at around the Planck length, 1.6*10^{-35} m, with possible violations of Lorentz invariance. Calculations of…
The hypothesis on a minimal scale existence in the Universe leads to noncommutative geometry of Spacetime and thence to a modification of the Special Relativity constraint. Sidharth has deduced that this is equivalent to the Lorentz…
We summarize theoretical and experimental work on tests of CPT and local Lorentz symmetry in gravity. Recent developments include extending the effective field theory framework into the nonlinear regime of gravity.
We continue our study of the Lorentz breaking string theories. These theories are defined as string theory with modified Hamiltonian constraint which breaks the Lorentz symmetry of target space-time. We analyze properties of this theory in…
This proceedings contribution summarizes recent investigations of Lorentz violation in matter-gravity couplings.
Tilted brane in theories with large compact extra dimensions leads to spontaneous symmetry breaking of the Lorentz and rotational invariance in four dimensions, as shown by Dvali and Shifman. In this brief report, we point out that the…
The violation of Lorentz symmetry can arise in a variety of approaches to fundamental physics. For the description of the associated low-energy effects, a dynamical framework known as the Standard-Model Extension has been developed. This…
The CPT theorem has been tested to very high precision in a variety of experiments involving particles and antiparticles confined within Penning traps. These tests include comparisons of anomalous magnetic moments and charge-to-mass ratios…