Improving the Drell-Yan probe of small x partons at the LHC via a k_t cut

TL;DR

This paper proposes a method to improve the measurement of low x parton distribution functions at the LHC by applying a transverse momentum cutoff to Drell-Yan lepton pairs, reducing theoretical uncertainties.

Contribution

It introduces a procedure using a k_t cut to enhance the sensitivity of Drell-Yan measurements to low x PDFs, accounting for Sudakov effects and scale uncertainties.

Findings

Enhanced sensitivity to low x PDFs at high rapidities

Reduced dependence on factorization scale choices

Effective probing of low scale, low x domain

Abstract

We show that the observation of the Drell-Yan production of low-mass lepton-pairs (M < 20 GeV) at high rapidities (Y > 3) at the LHC can make a direct measurement of parton distribution functions (PDFs) in the low x region, x < 10^{-4}. We describe a procedure that greatly reduces the sensitivity of the predictions to the choice of the factorization scale and, in particular, show how, by imposing a cutoff on the transverse momentum of the lepton-pair, the data are able to probe PDFs in the important low scale, low x domain. We include the effects of the Sudakov suppression factor.