Energy-momentum uncertainties as possible origin of threshold anomalies inUHECR and TeV-gamma events

A threshold anomaly refers to a theoretically expected energy threshold tha t is not observed experimentally. Here we offer an explanation of the thres hold anomalies encountered in the ultra-high energy cosmic ray events and t he TeV-gamma events, by arguing that energy-momentum uncertainties due to q uantum gravity, too small to be detected in low-energy regime, can affect p article kinematics so as to raise or even eliminate the energy thresholds. (C) 2001 Published by Elsevier Science B.V.