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Properties of the Scale Invariant O(g4) Lipatov Kernel

Claudio Coriano', Alan R. White

hep-pharXiv:hep-ph/9503294

Abstract

We study the scale-invariant O(g4) kernel which appears as an infra-red contribution in the BFKL evolution equation and is constructed via multiparticle t-channel unitarity. We detail the variety of Ward identity constraints and infra-red cancellations that characterize its infrared behaviour. We give an analytic form for the full non-forward kernel. For the forward kernel controlling parton evolution at small-x, we give an impact parameter representation, derive the eigenvalue spectrum, and demonstrate a holomorphic factorisation property related to conformal invariance. The results show that, at next-to-leading-order, the transverse momentum infra-red region may produce a strong reduction of the BFKL small-x behavior.

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