Progress towards 2 to 2 scattering at two-loops

Abstract

We discuss the two-loop integrals necessary for evaluating massless 2 to 2 scattering amplitudes. As a test process, we consider the leading colour two-loop contribution to qqbar to q'qbar'. We show that for physical scattering processes the two Smirnov-Veretin planar box graphs I1 and I2 are accompanied by factors of 1/(D-4) thereby necessitating a knowledge of both I1 and I2 to O(epsilon). Using an alternative basis I1 and the irreducible numerator integral I3, the factors of 1/(D-4) disappear.

Comments: 6 pages, latex, npb.sty, 3 postscript figures, contributed to proceedings of "Loops and Legs in Quantum Field Theory", Bastei, Germany, April 9-14, 2000