Derivation of a Vacuum Refractive Index in a Stringy Space-Time Foam Model
arXiv:0804.3566 · doi:10.1016/j.physletb.2008.06.029
Abstract
It has been suggested that energetic photons propagating in vacuo should experience a non-trivial refractive index due to the foamy structure of space-time induced by quantum-gravitational fluctuations. The sensitivity of recent astrophysical observations, particularly of AGN Mk501 by the MAGIC Collaboration, approaches the Planck scale for a refractive index depending linearly on the photon energy. We present here a new derivation of this quantum-gravitational vacuum refraction index, based on a stringy analogue of the interaction of a photon with internal degrees of freedom in a conventional medium. We model the space-time foam as a gas of D-particles in the bulk space-time of a higher-dimensional cosmology where the observable Universe is a D3-brane. The interaction of an open string representing a photon with a D-particle stretches and excites the string, which subsequently decays and re-emits the photon with a time delay that increases linearly with the photon energy and is related to stringy uncertainty principles. We relate this derivation to other descriptions of the quantum-gravitational refractive index in vacuo.
8 pages, 3 eps figures
References in corpus (6)
- Lorentz-violation-induced arrival delays of cosmological particles
- Superluminality and UV Completion
- The Refractive Index of Curved Spacetime: the Fate of Causality in QED
- Causality and Micro-Causality in Curved Spacetime
- New constraints on Planck-scale Lorentz Violation in QED from the Crab Nebula
- Relativistic Modified Newtonian Dynamics from String Theory?
Cited by in corpus (16)
- Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope
- Prospects for constraining quantum gravity dispersion with near term observations
- Lorentz Violation and Ultrahigh-Energy Photons
- Time Delays of Strings in D-particle Backgrounds and Vacuum Refractive Indices
- Probes of Lorentz Violation in Neutrino Propagation
- Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation
- Probing a Possible Vacuum Refractive Index with Gamma-Ray Telescopes
- Planck-scale Lorentz violation constrained by Ultra-High-Energy Cosmic Rays
- The Photon Sector in the Quantum Myers-Pospelov Model: An improved description
- Flavour Condensates in Brane Models and Dark Energy
- CPT Violation and Decoherence in Quantum Gravity
- Non-extensive statistics in stringy space-time foam models and entangled meson states
- A note on particle kinematics in Horava-Lifshitz scenarios
- Bulk photons in Asymmetrically Warped Space-times and Non-trivial Vacuum Refractive Index
- Exploration of Possible Quantum Gravity Effects with Neutrinos II: Lorentz Violation in Neutrino Propagation
- The Omega Effect for Neutral Mesons