EXACT AND APPROXIMATE EXPRESSIONS FOR MULTIGLUON SCATTERING

In this paper we use a previously introduced recursive method to obtain building blocks from which n-gluon scattering amplitudes can be constructed. The method is discussed in detail for 6,7 and 8 gluons. For 7 gluons - a process with 2485 diagrams - exact analytic results are given. A general method for the colour summation is presented. With the exact results for 7 gluons comparisons are made with approximate calculations for the total cross section as well as for distributions. The approximate calculations turn out to describe many distributions well, but not the normalization. We also study the difference between the exact colour treatment and the approximation of leading order in N for the SU(N) gauge group. The latter comparison is pursued up to 9 gluons. © 1990.