Implications of Spacetime Quantization for the Bahcall-Waxman Neutrino Bound

There is growing interest in quantum-spacetime models in which small departures from Lorentz symmetry are governed by the Planck scale. In particular, several studies have considered the possibility that these small violations of Lorentz symmetry may affect various astrophysical observations, such as the evaluation of the GZK limit for cosmic rays, the interaction of TeV photons with the Far Infrared Background and the arrival time of photons with different energies from cosmological sources. We show that the same Planck-scale departures from Lorentz symmetry that lead to a modification of the GZK limit which would be consistent with the observations reported by AGASA, also have significant implications for the evaluation of the Bahcall-Waxman bound on the flux of high-energy neutrinos produced by photo-meson interactions in sources of size not much larger than the proton photo-meson mean free path.