Non-perturbative contributions to vector-boson transverse momentum spectra in hadronic collisions

Francesco Hautmann,Ignazio Scimemi,Alexey Vladimirov

doi:10.1016/j.physletb.2020.135478

Francesco Hautmann, Ignazio Scimemi + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2020.135478

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Abstract

Experimental measurements of Drell-Yan (DY) vector-boson production are available from the Large Hadron Collider (LHC) and from lower-energy collider and fixed-target experiments. In the region of low vector-boson transverse momenta qT, which is important for the extraction of the W-boson mass at the LHC, QCD contributions from non-perturbative Sudakov form factors and intrinsic transverse momentum distributions become relevant. We study the potential for determining such contributions from fits to LHC and lower-energy experimental data, using the framework of low-qT factorization for DY differential cross sections in terms of transverse momentum dependent (TMD) distribution functions. We investigate correlations between different sources of TMD non-perturbative effects, and correlations with collinear parton distributions. We stress the relevance of accurate DY measurements at low masses and with fine binning in transverse momentum for improved determinations of long-distance contributions to Sudakov evolution processes and TMDs.

Highlights

The production of photons, weak bosons and leptons at large momentum transfer QQCD in high-energy hadronic collisions is described successfully by factorization [1] of short-distance hard-scattering cross sections, computable at finite order in QCD perturbation theory as power series expansions in the strong coupling αs, and non-perturbative long-distance parton distribution functions (PDFs), determined from fits to experiment
These amount to i) perturbative logarithmically-enhanced corrections in αsk lnm Q /qT (m ≤ 2k), which go beyond finite-order perturbation theory and call for summation to all orders in αs, and ii) non-perturbative contributions besides PDFs, which correspond to the intrinsic transverse momentum distributions in the initial states of the collision and to non-perturbative components of Sudakov form factors
Nonperturbative effects besides PDFs in DY production are included in the formalism of transverse momentum dependent (TMD) parton distribution functions [9]

Summary

Introduction

QCD in high-energy hadronic collisions is described successfully by factorization [1] of short-distance hard-scattering cross sections, computable at finite order in QCD perturbation theory as power series expansions in the strong coupling αs, and non-perturbative long-distance parton distribution functions (PDFs), determined from fits to experiment. The purpose of this work is to examine the combined determination of the nonperturbative rapidity-evolution kernel and intrinsic transverse momentum kT distribution from fits to measurements of transverse momentum spectra in DY lepton-pair production at the Large Hadron Collider (LHC) and in lower-energy experiments, including Tevatron, RHIC and fixed-target experiments. To this end, we employ the calculational framework developed in [15,16,17,18,19,20].

Theoretical inputs

Determination of fNP and DNP from fits to experiment

Conclusion