Longitudinal Z-boson polarization and the Higgs boson production cross-section

TL;DR

This paper explores how measuring the Z boson polarization via the Drell-Yan process at the LHC can significantly improve the precision of the gluon parton distribution function, thereby reducing uncertainties in Higgs boson production predictions.

Contribution

It introduces a novel method using the Z boson polarization observable to enhance gluon PDF determination at the LHC and HL-LHC.

Findings

Potential to reduce Higgs cross-section PDF uncertainty by over 50%

Demonstrates the sensitivity of the $A_0$ observable to gluon PDFs

Provides a detailed numerical analysis using xFitter platform

Abstract

We present a study of the LHC (and HL-LHC) potential towards a precise determination of the gluon parton distribution function of the proton at intermediate Bjorken-$x$ from measurements of Drell-Yan production. To this extent, we exploit a clean and theoretically well predicted observable: the Drell-Yan lepton angular coefficient $A_0$, associated with the longitudinal polarization of the Z boson. Through a detailed numerical analysis using the open-source xFitter platform, we illustrate how this observable can provide significant sensitivity over current determinations of the gluon PDF, and a reduction in the PDF uncertainty on the Higgs boson production cross-section by a factor of over 50\%.