It has been speculated that Lorentz-invariance violation (LIV) might be generated by quantum-gravity (QG) effects. As a consequence, particles may not travel at the universal speed of light. In particular, superluminal extragalactic neutrinos would rapidly lose energy via the bremssthralung of electron-positron pairs (ν→νe+e-), damping their initial energy into electromagnetic cascades, a figure constrained by Fermi-Large Area Telescope data. We show that the two cascade neutrino events with energies around 1 PeV recently detected by IceCube - if attributed to extragalactic diffuse events, as it appears likely - can place the strongest bound on LIV in the neutrino sector, namely, δ=(v2-1)<O(10 -18), corresponding to a QG scale MQG 105MPl (MQG 10-4MPl) for a linear (quadratic) LIV, at least for models inducing superluminal neutrino effects (δ>0).
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Jun 24 2013|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)