Small-$x$ resummation from HELL

TL;DR

This paper introduces a framework and a computer code, HELL, for performing small-x resummation in parton evolution and coefficient functions, relevant for high-energy collider physics and recent DIS data.

Contribution

It develops a comprehensive small-x resummation framework implemented in HELL, improving predictions for parton densities and structure functions at high energies.

Findings

Resummed DGLAP splitting functions presented

Matched results for DIS structure functions shown

Framework applicable to high-energy collider phenomenology

Abstract

Small-$x$ logarithmic enhancements arising from high-energy gluon emissions affect both the evolution of collinearly-factorized parton densities and partonic coefficient functions. With the higher collider energy reached by the LHC, the prospect of a future high-energy collider, and the recent deep-inelastic scattering (DIS) results at small-$x$ from HERA, providing phenomenological tools for performing small-$x$ resummation has become of great relevance. In this paper we discuss a framework to perform small-$x$ resummation for both parton evolution and partonic coefficient functions and we describe its implementation in a computer code named High-Energy Large Logarithms (HELL). We present resummed and matched results for the DGLAP splitting functions and, as a proof of principle, for the massless structure functions in DIS.