Energy-momentum uncertainties as possible origin of threshold anomalies   in UHECR and TeV-gamma ray events
  A threshold anomaly refers to a theoretically expected energy threshold that is not observed experimentally. Here we offer an explanation of the threshold anomalies encountered in the ultra-high energy cosmic ray events and the TeV-gamma ray events, by arguing that energy-momentum uncertainties due to quantum gravity, too small to be detected in low-energy regime, can affect particle kinematics so as to raise or even eliminate the energy thresholds. A possible modification of the energy-momentum dispersion relation, giving rise to time-of-flight differences between photons of different energies from gamma ray bursts, is also discussed. 
Y. Jack Ng (University of North Carolina), D.-S. Lee (National Dong   Hwa University), M.C. Oh (UNC), and H. van Dam (UNC)