Related papers: Cosmic Rays and the Structure of Space-Time
The current effort to test General Relativity employs multiple disparate formalisms for different observables, obscuring the relations between laboratory, astrophysical and cosmological constraints. To remedy this situation, we develop a…
Special relativity has been tested at low energy with great accuracy, but these results cannot be extrapolated to very high-energy phenomena: this new domain of physics may actually provide the key to the, yet unsettled, question of the…
Recent work has shown that dispersion relations with Planck scale Lorentz violation can produce observable effects at energies many orders of magnitude below the Planck energy M. This opens a window on physics that may reveal quantum…
We investigate the conditions under which cosmological variations in physical `constants' and scalar fields are detectable on the surface of local gravitationally-bound systems, such as planets, in non-spherically symmetric background…
Many theoretical approaches to quantum gravity predict the breakdown of Lorentz symmetry at Planck energies. Kinematical cosmic-ray studies are a sensitive tool in the search for such effects. This talk discusses the construction of test…
The dramatic confrontation between new observations and theories of the early and recent universe makes cosmology one of the most rapidly advancing fields in the physical sciences. The universe is a unique laboratory in which to probe…
Combined data from gamma-ray telescopes and cosmic-ray detectors have produced some new surprising insights regarding intergalactic and galactic magnetic fields, as well as extragalactic background light. We review some recent advances,…
The topic of Lorentz invariance violation is a fundamental question in physics that has taken on particular interest in theoretical explorations of quantum gravity scenarios. I discuss various gamma-ray observations that give limits on…
Cosmic rays interacting with the atmosphere allow for the probing of fundamental interactions at ultra-high energies. We thus obtain limits on strongly coupled new physics models via their imprints on cosmic-ray air showers. Using the Monte…
This talk discusses the relation between spacetime-dependent scalars, such as couplings or fields, and the violation of Lorentz symmetry. A specific cosmological supergravity model demonstrates how scalar fields can acquire time-dependent…
An important open question in fundamental physics concerns the nature of spacetime at distance scales associated with the Planck length. The widespread belief that probing such distances necessitates Planck-energy particles has impeded…
The physics of Ultra High Energy Cosmic Rays will be reviewed, discussing the latest experimental results and theoretical models aiming at explaining the observations in terms of spectra, mass composition and possible sources. It will be…
Close to the Planck energy scale, the quantum nature of space-time reveals itself and all forces, including gravity, should be unified so that all interactions correspond to just one underlying symmetry. In the absence of a full quantum…
This is an introductory review about the on-going search for a signal of Lorentz Invariance Violation (LIV) in cosmic rays. We first summarise basic aspects of cosmic rays, focusing on rays of ultra high energy (UHECRs). We discuss the…
Internal (non-geometric) symmetry is recognized and studied as a new phenomenon in cosmology. Symmetry relates cosmic vacuum to non-vacuum forms of cosmic energies, which are dark matter, baryons, and radiation. It is argued that the origin…
Lorentz symmetry violation (LSV) at Planck scale can be tested (see e.g. physics/0003080) through ultra-high energy cosmic rays (UHECR). In a deformed Lorentz symmetry (DLS) pattern where the effective LSV parameter varies like the square…
We discuss the threshold anomaly in ultra-high energy cosmic ray physics by assuming that the matter world just be perturbation of a de Sitter universe, which is consistent with the recent astronomical observations: about two thirds of the…
We show that a tiny but non-zero positive cosmological constant, which has been strongly suggested by the recent astronomical observations on supernovae and CMBR, may change notably the behaviors of the ultrahigh energy cosmic ray…
This year we are celebrating 101 years since the discovery of cosmic rays. They are whizzing all around the Universe, and they occur at very different energies, including the highest particle energies that exist. However, theory predicts an…
Gamma ray bursts are excellent candidates to constrain physical models which break Lorentz symmetry. We consider deformed dispersion relations which break the boost invariance and lead to an energy-dependent speed of light. In these models,…