Abstract
Lorentz symmetry breaking at very high energies may lead to photon dispersion relations of the form with new terms suppressed by a power of the Planck mass . We show that first and second order terms of size and , respectively, would lead to a photon component in cosmic rays above that should already have been detected, if corresponding terms for are significantly smaller. This suggests that LI breaking suppressed up to second order in the Planck scale is unlikely to be phenomenologically viable for photons.
- Received 13 August 2007
DOI:https://doi.org/10.1103/PhysRevLett.100.021102
©2008 American Physical Society