Rapidity-separation dependence and the large next-to-leading corrections to the BFKL equation - art. no. 074003

Recent concerns about the very large next-to-leading logarithmic (NLL) corr ections to the BFKL equation are addressed by the introduction of a physica l rapidity-separation parameter Delta. At the leading logarithm (LL) this p arameter enforces the constraint that successive emitted gluons have a mini mum separation in rapidity, y(i+1)-y(i)>Delta. The most significant effect is to reduce the BFKL Pomeron intercept from the standard result as Delta i s increased from 0 (standard BFKL). At NLL this Delta-dependence is compens ated by a modification of the BFKL kernel, such that the total dependence o n Delta is formally next-to-next-to-leading logarithmic. In this formulatio n, as long as Delta greater than or similar to 22.2 (for alpha(s)=0.15), (i ) the NLL BFKL Pomeron intercept is stable with respect to variations of De lta, and (ii) the NLL correction is small compared to the LL result. Implic ations for the applicability of the BFKL resummation to phenomenology are c onsidered. [S0556-2821(99)01817-2].