Related papers: Spacetime-varying couplings and Lorentz violation
We show that it is possible to steer clear of a spacetime singularity during gravitational collapse by considering the time-variation of a fundamental coupling, in this case, the fine structure constant {\alpha}. We study a spherical…
Crossover quintessence predicts that the time variation of fundamental couplings is substantially faster at redshift $z\approx 2$ than over the past few billion years. This could reconcile the reported time variation of the fine structure…
We discuss the implications of a recently proposed pattern of Lorentz symmetry violation on very high-energy cross sections. As a consequence of the breaking of local Lorentz invariance by the introduction of a fundamental length, $a$ , the…
Astrophysical observations are a powerful tool to constrain effects of Lorentz-invariance violation in the photon sector. Objects at high redshifts provide the longest possible baselines, and gamma-ray telescopes allow us to observe some of…
The physical mechanism of phenomenon is explained as a result of inequality of forward and reversed processes in optics. The importance of experimental study of its invariance relation is discussed.
Time and space translation invariance, giving rise to energy and momentum conservation, are not only amongst the most fundamental but also the most generally accepted symmetry assumptions in physics. It is nevertheless prudent to put such…
In this work, we investigate a theory of linear Weyl gravity coupled to a scalar field and study the scenario in which Lorentz symmetry is broken by a non-vanishing vacuum expectation value of the Weyl field in the flat space limit after…
Although Lorentz symmetry has been tested at low energy with extremely good accuracy, its validity at very high energy is much less well established. If Lorentz symmetry violation (LSV) is energy-dependent (e.g. $\propto E^2$), it can be of…
Some solutions to the anomalies of ultra high energy cosmic-ray(UHECR) and TeV $\gamma$-rays require disturbed non-quadratic dispersion relations, which suggest the Lorentz violation. Also, some new theories such as quantum gravity, string…
Violations of spacetime symmetries have recently been identified as promising signatures for physics underlying the Standard Model. The present talk gives an overview over various topics in this field: The motivations for spacetime-symmetry…
Some of the recent work on quantum gravity has involved modified uncertainty relations such that the products of the uncertainties of certain pairs of observables increase with time. It is here observed that this type of modified…
Violations of Lorentz symmetry are typically associated with modifications of one-particle dispersion relations. The physical effects of such modifications in particle collisions often grow with energy, so that ultrahigh-energy cosmic rays…
We examine the general issue of whether a scale dependent cosmological constant can be consistent with general covariance, a problem that arises naturally in the treatment of quantum gravitation where coupling constants generally run as a…
In this brief review I discuss ways and tests of CPT-Violation in the context of quantum gravity theories with space-time foam vacua, which entail quantum decoherence of matter propagating in such backgrounds. I cover a wide variety of…
A simple model is constructed which allows to compute modified dispersion relations with effects from loop quantum gravity. Different quantization choices can be realized and their effects on the order of corrections studied explicitly. A…
New phenomenological models of Quantum Gravity have suggested that a Lorentz-Invariant discrete spacetime structure may become manifest through a nonstandard coupling of matter fields and spacetime curvature. On the other hand, there is…
This talk at the CPT'25 meeting presents an overview of some recent results in Lorentz and CPT violation. Topics covered include the geometry of Finsler spaces associated with Lorentz violation, the resolution of the concordance problem in…
The dipole anomaly in the power spectrum of CMB may indicate that the Lorentz boost invarianc is violated at cosmic scale. We assume that the Lorentz symmetry is violated partly from the scale of galaxy. We employ the symmetry of very…
Bluhm-Kostelecky (BK) Lagrangian to test Lorentz violation with spin-polarised test bodies is shown to be transformed to a torsion-coupling constant Lagrangian by taking into account the Fock-Ivanenko coefficients in spinor form. In this…
Cosmological limits on Lorentz invariance breaking in Chern-Simons $(3+1)-dimensional$ electrodynamics are used to place limits on torsion. Birefrigence phenomena is discussed by using extending the propagation equation to Riemann-Cartan…