The Soft Anomalous Dimension at four loops in the Regge Limit

Abstract

The soft anomalous dimension governs the infrared divergences of scattering amplitudes in general kinematics to all orders in perturbation theory. By comparing the recent Regge-limit results for 2\to22→2 scattering (through Next-to-Next-to-Leading Logarithms) in full colour to a general form for the soft anomalous dimension at four loops we derive powerful constraints on its kinematic dependence, opening the way for a bootstrap-based determination.

Colour structure of three-reggeon cuts in QCD

“…The momentum parts of the three-Reggeon contributions are calculated in the two and three loops in [15], [19], [20] and in [16], and in four loops (see Figs. (3) and ( 4)) in [21], [22], [23] and in [24], [25], [26], [27] [28].…”