On The Recently Discovered Correlations Between Gamma-Ray And X-Ray   Properties Of Gamma Ray Bursts
  Recently, several new correlations between the observed $\gamma$-ray and the X-ray properties of gamma-ray bursts (GRBs) were inferred from a comprehensive analysis of the X-ray light curves of more than 650 GRBs measured with the Swift X-ray telescope (Swift/XRT) during the years 2004-2010. Like previously well established correlations, they challenge GRB models. Here we show that in the cannonball (CB) model of GRBs, the newly discovered correlations and those that follow from them, have the same simple kinematic origin as those discovered earlier. They result from the strong dependence of the observed radiations on the bulk motion Lorentz and Doppler factors of the jet of highly relativistic plasmoids (CBs) that produces these radiations by interaction with the medium through which it propagates. 
Shlomo Dado and Arnon Dar
astro-ph.HE