Baryonic loading and e^+e^- rate equation in GRB sources

The expansion of the electron-positron plasma in the GRB phenomenon is compared and contrasted in the treatments of Mészáros, Laguna and Rees, of Shemi, Piran and Narayan, and of Ruffini et al. The role of the correct numerical integration of the hydrodynamical equations, as well as of the rate equation for the electron-positron plasma loaded with a baryonic mass, are outlined and confronted for crucial differences. © 2008 Springer-Verlag Berlin Heidelberg.