The GRB Variability/Peak Luminosity Correlation: new results
  We report test results of the correlation between time variability and peak luminosity of Gamma-Ray Bursts (GRBs), using a larger sample (32) of GRBs with known redshift than that available to Reichart et al. (2001), and using as variability measure that introduced by these authors. The results are puzzling. Assuming an isotropic-equivalent peak luminosity, as done by Reichart et al. (2001), a correlation is still found, but it is less relevant, and inconsistent with a power law as previously reported. Assuming as peak luminosity that corrected for GRB beaming for a subset of 16 GRBs with known beaming angle, the correlation becomes little less significant. 
C. Guidorzi, F. Frontera, E. Montanari, F. Rossi, L. Amati, A. Gomboc,   K. Hurley, C.G. Mundell