Threshold behaviour of rotational cross sections in e--H2scattering

Rotational excitation cross sections, in the e - -H 2 system, are evaluated within a recently suggested off-shell formalism. Numerical results of the theory are generally found in good agreement with close-coupling values of the literature. It is found, in particular, that total cross sections correctly tend to zero at threshold and that angular distributions present, at low energies, deep minima in the forward direction. Such characteristic features of the theory are physically interpreted.