Higher Order Effects in Non Linear Evolution from a Veto in Rapidities

Abstract

Higher order corrections to the Balitsky-Kovchegov equation have been estimated by introducing a rapidity veto which forbids subsequent emissions to be very close in rapidity and is known to mimic higher order corrections to the linear BFKL equation. The rapidity veto constraint has been first introduced using analytical arguments obtaining a power growth with energy, Q_s (Y) ~ exp(lambda Y), of the saturation scale of lambda ~ 0.45. Then a numerical analysis for the non-linear Balitsky-Kovchegov equation has been carried out for phenomenological rapidities: when a veto of about two units of rapidity is introduced for a fixed value of the coupling constant of alpha_s = 0.2 the saturation scale lambda decreases from ~ 0.6 to ~ 0.3, and when running coupling effects are taken into account it decreases from ~ 0.4 to ~ 0.3.