A $p_T$-ratio observable for studies of intrinsic transverse momentum of partons from Drell-Yan $p_T$ spectra

TL;DR

This paper proposes a new ratio-based observable for Drell-Yan $p_T$ spectra that enhances sensitivity to intrinsic transverse momentum of partons while reducing systematic uncertainties.

Contribution

It introduces a novel $p_T$ ratio observable that improves the measurement of intrinsic transverse momentum distributions in Drell-Yan processes.

Findings

The $p_T$ ratio observable reduces systematic uncertainties.

It provides improved sensitivity to intrinsic transverse momentum.

The method is applicable to low-$p_T$ measurements in Drell-Yan data.

Abstract

The determination of the intrinsic transverse momentum distribution of partons is central both for applications of parton shower Monte Carlo generators and for QCD studies of transverse momentum dependent (TMD) parton densities. Valuable information on this distribution is provided by experimental measurements of Drell-Yan transverse momentum $p_T$, in the region of low transverse momenta, with fine binning in $p_T$. However, such fine-binning measurements are challenging, as they require an extremely delicate control of systematic uncertainties. We suggest a $p_T$ observable based on measuring ratios between cross sections of suitably defined low-$p_T$ and high-$p_T$ regions. This observable does not rely on any dedicated partition of bins and has lower systematic uncertainties, and is shown to provide a good sensitivity to the intrinsic transverse momentum.