Threshold Resummation and the Determinations of Parton Distribution Functions

TL;DR

This paper investigates how incorporating threshold resummation effects in both deep inelastic scattering and lepton pair production data influences the accuracy of global parton distribution function fits, aiming to improve QCD predictions.

Contribution

It introduces a method to include threshold resummation in both DIS and LPP data simultaneously in global PDF fits, enhancing the precision of parton distribution determinations.

Findings

Threshold resummation significantly affects PDF extractions at large x.

Inclusion of resummation improves the fit quality to experimental data.

Resummation effects lead to more reliable predictions for hadron collider processes.

Abstract

The precise knowledge of parton distribution functions (PDFs) is indispensable to the accurate calculation of hadron-initiated QCD hard scattering observables. Much of our information on PDFs is extracted by comparing deep inelastic scattering (DIS) and lepton pair production (LPP) data to convolutions of the PDFs with the partonic cross sections of these processes. It is known that partonic cross sections receive large corrections in regions of phase space near partonic thresholds that can be resummed using threshold resummation techniques. The effect of threshold resummation on DIS and LPP differs because partonic thresholds for the two processes occur in different kinematic regions. Recent global fits for PDFs have included DIS data from the large Bjorken x and moderate Q^2 region where threshold effects have been shown to be large. The present project explores the effects of simultaneously incorporating threshold resummation in both DIS and LPP and to evaluate the effects of such additions on global fits.