Violations of Lorentz invariance in the neutrino sector: an improved analysis of anomalous threshold constraints

Abstract

Abstract.Recently there has been a renewed activity in the physics of violations of Lorentz invariance in the neutrino sector. Flavor dependent Lorentz violation, which generically changes the pattern of neutrino oscillations, is extremely tightly constrained by oscillation experiments. Flavor independent Lorentz violation, which does not introduce new oscillation phenomena, is much more weakly constrained with constraints coming from time of flight and anomalous threshold analyses. We use a simplified rotationally invariant model to investigate the effects of finite baselines and energy dependent dispersion on anomalous reaction rates in long baseline experiments and show numerically that anomalous reactions do not necessarily cut off the spectrum quite as sharply as currently assumed. We also present a revised analysis of how anomalous reactions can be used to cast constraints from the observed atmospheric high energy neutrinos and the expected cosmogenic ones.

Use of energy loss mechanisms to constrain Lorentz invariance violations

“…[23] with the analytical model presented in this paper. The spectrum of that simulation for the energy-independent speed case (n = 2 in the notation of Ref.…”

“…In Ref. [23], on the contrary, the data are Monte Carlo simulated, and it is pointed out that the final energy in Eq. (6) does not have a sharp cut-off in the spectrum because of the finiteness of the baseline experiment (note, however, that according to Eqs.…”

“…If the energy loss increases with the amount of Lorentz invariance violation, the observations of high energy particles may be used to place limits on the size of the Lorentz invariant violating parameters (see Refs. [18][19][20][21][22][23][24]). Reactions of this sort include: photon and neutrino splitting (γ → 3γ and ν l → ν l ν l ν l ), photon production by charged leptons and neutrinos (e ± → e ± γ and ν l → ν l γ), and pair production by neutrinos (ν l → ν l e + e − ), which will be the one we will use hereafter when specific information is needed; we refer the reader to Ref.…”

Lorentz invariance violation and IceCube neutrino events

“…For the superluminal case, it has been shown [11,12] that the presence of the extra terms in the dispersion results in a suppression of π and K decay widths. The phase space suppression for both the subluminal and superluminal dispersions for meson decay and the Cerenkov process ν → νe + e − has been noticed in [9,[13][14][15][16] with limits on Lorentz violation parameters from IceCube events. A comprehensive listing of Lorentz and CPT violating operators and their experimental constraints is given in [17].…”

“…We assume identical ξ 3 for all the species of ν (andν) to avoid an extra source for neutrino oscillations which is not observed [16,22]. The amplitude for the process µ − (p) → e − (k )ν e (k)ν µ (p ) is given as,…”