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

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.

Contribution to the 2025 QCD session of the 59th Rencontres de Moriond. Based on the work in arXiv:2412.19060, published in Phys. Rev. D 111, 036018