Gamma and cosmic-ray tests of special relativity

Abstract

Lorentz symmetry violation (LSV) at Planck scale can be tested (see e.g. physics/0003080) through ultra-high energy cosmic rays (UHECR). In a deformed Lorentz symmetry (DLS) pattern where the effective LSV parameter varies like the square of the momentum scale (quadratically deformed relativistic kinematics, QDRK), a ≈10−6 LSV at Planck scale would be enough to produce observable effects on the properties of cosmic rays at the ≈1020 eV scale: absence of GZK cutoff, stability of unstable particles, lower interaction rates, kinematical failure of any parton model and of standard formulas for Lorentz contraction and time dilation… . Its phenomenological implications are compatible with existing data. If the effective LSV parameter is taken to vary linearly with the momentum scale (linearly deformed relativistic kinematics, LDRK), a LSV at Planck scale larger than ≈10−7 seems to lead to contradictions with data above ≈ TeV energies. Consequences are important for high-energy gamma-ray experiments, as well as ...