New twosided bound on the isotropic Lorentzviolating parameter of modified Maxwell theory
Abstract
There is a unique Lorentzviolating modification of the Maxwell theory of photons, which maintains gauge invariance, CPT, and renormalizability. Restricting the modifiedMaxwell theory to the isotropic sector and adding a standard spin(1)/(2) Dirac particle p^{±} with minimal coupling to the nonstandard photon γ∼, the resulting modifiedquantumelectrodynamics model involves a single dimensionless “deformation parameter,” κ∼_{tr}. The exact treelevel decay rates for two processes have been calculated: vacuum Cherenkov radiation p^{±}→p^{±}γ∼ for the case of positive κ∼_{tr} and photon decay γ∼→p^{+}p^{} for the case of negative κ∼_{tr}. From the inferred absence of these decays for a particular highquality ultrahighenergycosmicray event detected at the Pierre Auger Observatory and a wellestablished excess of TeV gammaray events observed by the High Energy Stereoscopic System telescopes, a twosided bound on κ∼_{tr} is obtained, which improves by 8 orders of magnitude upon the best direct laboratory bound. The implications of this result are briefly discussed.
 Publication:

Physical Review D
 Pub Date:
 October 2008
 DOI:
 10.1103/PhysRevD.78.085026
 arXiv:
 arXiv:0809.3217
 Bibcode:
 2008PhRvD..78h5026K
 Keywords:

 11.30.Cp;
 12.20.m;
 98.70.Rz;
 98.70.Sa;
 Lorentz and Poincare invariance;
 Quantum electrodynamics;
 gammaray sources;
 gammaray bursts;
 Cosmic rays;
 High Energy Physics  Phenomenology;
 Astrophysics;
 High Energy Physics  Theory
 EPrint:
 18 pages, v5: published version in preprint style