Expanding running coupling effects in the hard Pomeron

We study QCD hard processes at scales of order k ≫ Λ in the limit in which the beta-function coefficient b is taken to be small, but ᾱs(k ) is kept fixed. The (nonperturbative) Pomeron is exponentially suppressed in this limit, making it possible to define purely perturbative high-energy Green’s functions. The hard Pomeron exponent acquires diffusion and running coupling corrections which can be expanded in the b parameter and turn out to be dependent on the effective coupling bᾱ sY . We provide a general setup for this b-expansion and we calculate the first few terms both analytically and numerically.