How accurately can we measure the W cross section?
S. Frixione, M. L. Mangano
TL;DR
This paper investigates QCD-driven systematic uncertainties in measuring the W cross section at hadron colliders by focusing on acceptance corrections required to convert observed events into total production rates. It compares four theoretical treatments—LO, LO+HERWIG, NLO, and MC@NLO—across Tevatron and LHC-like cuts, incorporating spin correlations, W width, and different PDFs, to quantify how NLO effects and parton showering modify acceptances and differential distributions. The findings demonstrate that naive fixed-order calculations can mispredict lepton-level observables if spin correlations are neglected and that matched NLO+shower approaches are essential for reliable acceptance estimates. The work informs precision W cross-section measurements and luminosity-monitoring strategies by highlighting the need for realistic, higher-order simulations in experimental analyses.
Abstract
We study the QCD sources of systematic uncertainties in the experimental extraction of the W cross section at hadron colliders. The uncertainties appear in the evaluation of the detector acceptances used to convert the number of observed events into a total production cross section. We consider the effect of NLO corrections, as well as of the inclusion of parton showers, and evaluate the impact of spin correlations and of PDF and scale uncertainties.