Drell-Yan as a probe of small x partons at the LHC

TL;DR

This paper demonstrates how fixing the factorization scale in Drell-Yan production at the LHC reduces theoretical uncertainties, enabling direct measurements of low-x parton distribution functions.

Contribution

It introduces a method to fix the factorization scale using NLO matrix elements, improving the reliability of low-x parton distribution measurements.

Findings

Reduced sensitivity to scale choices in Drell-Yan predictions

Enhanced ability to probe low-x parton distributions

Method applicable to high-rapidity, low-mass lepton-pair production

Abstract

The predictions of Drell-Yan production of low-mass, lepton-pairs, at high rapidity at the LHC, are known to depend sensitively on the choice of factorization and renormalization scales. We show how this sensitivity can be greatly reduced by fixing the factorization scale of the LO contribution based on the known NLO matrix element, so that observations of this process at the LHC can make direct measurements of parton distribution functions in the low x domain; x less than about 10^{-4}.