ASTROPHYSICAL LIMIT ON THE DEFORMATION OF THE POINCARE GROUP

The deformed Poincare group contains a characteristic mass, kappa. At energies exceeding kappa, deviations from the special theory of relativity become significant. However, small deviations from ordinary relativistic kinematics are observable even at energies substantially lower than kappa. The observation of distant events producing ultra high energy (UHE) particles leads to a lower limit on kappa. From an analysis of the UHE data on the burst in the binary system Her X-1 in 1986, we deduce kappa greater than or similar to 10(12) GeV.