Constraining Parton Distribution Functions from Neutral Current Drell-Yan Measurements

TL;DR

This paper demonstrates that measurements of cross sections and forward-backward asymmetries in Drell-Yan processes at the LHC can effectively constrain proton parton distribution functions across a broad range of kinematic variables, with current data already competitive.

Contribution

It introduces a method to use Drell-Yan measurements at the LHC to improve constraints on proton PDFs across various invariant mass regions.

Findings

Current measurements have competitive statistical errors.

Future data will further tighten PDF constraints.

Applicable to both on-peak and off-peak mass regions.

Abstract

We study the cross section \sigma and Forward-Backward asymmetry A_{FB} in the process pp \to \gamma^*,Z \to \ell^+\ell^- (with \ell=e,\mu) for determinations of Parton Distribution Functions (PDFs) of the proton. We show that, once mapped in the invariant mass of the di-lepton final state, M({\ell\ell}), both observables, \sigma and A_{FB}, display a statistical error which is presently competitive with that assigned to the existing PDF sets and which will rapidly become smaller than the latter as the luminosity being accumulated at Run-II of the LHC grows. This statement is applicable to both on-peak and off-peak M({\ell\ell}) regions, both (just) below and above it, thereby offering a means of constraining the quark PDFs over a sizeable (x,Q^2) range.