Twist decomposition of proton structure from BFKL and BK amplitudes

TL;DR

This paper performs a twist decomposition of the BK amplitude in the double logarithmic limit, deriving compact expressions for higher twist contributions and comparing them to saturation models, revealing smaller higher twist effects.

Contribution

It provides the first detailed twist decomposition of BFKL/BK amplitudes in the double logarithmic limit with analytic expressions for higher twists.

Findings

Higher twist amplitudes are significantly smaller than saturation model predictions.

Derived compact analytic formulas for twist decomposition.

Validated the accuracy of the approximations for higher twist contributions.

Abstract

An analysis of twist composition of Balitsky-Kovchegov (BK) amplitude is performed in the double logarithmic limit. In this limit the BK evolution of color dipole -- proton scattering is equivalent to BFKL evolution which follows from vanishing of the Bartels vertex in the collinear limit. We perform twist decomposition of the BFKL/BK amplitude for proton structure functions and find compact analytic expressions that provide accurate approximations for higher twist amplitudes. The BFKL/BK higher twist amplitudes are much smaller than those following from eikonal saturation models.