RESUMMATION AT LARGE-Q AND AT SMALL-X

We propose a unified and simple viewpoint to various evolution equatio ns appropriate in different kinematic regions. We show that the resumm ation technique reduces to the Altarelli-Parisi equation, if the trans verse degrees of freedom of a parton are ignored, to the Balitskii-Fad in-Kuraev-lipatov equation, if the momentum fraction of a parton vanis hes, and to the Gribov-Levin-Ryskin equation, if the recombination of gluons is included. (C) 1997 Elsevier Science B.V.