W+charm production with massive c quarks in PowHel

TL;DR

This paper presents a NLO QCD accurate simulation of W boson production with charm quarks at the LHC, incorporating finite charm mass, off-shell effects, and spin correlations, and compares predictions with ATLAS and CMS data.

Contribution

The implementation of W+c production in PowHel with matching to PYTHIA8, including finite charm mass and off-shell effects, is a novel advancement for precise collider predictions.

Findings

Good agreement with ATLAS and CMS data within uncertainties

No immediate need to modify strange quark PDFs based on current data

Provides a detailed theoretical framework for W+c production analysis

Abstract

The hadroproduction of a $W$ boson in association with a charm quark at the Large Hadron Collider is at the centre of current investigations due to its potential to probe the strangeness content of the proton. In this paper we present an implementation of the $W+c$ production process in the PowHel event generator matched to the PYTHIA8 parton shower approach, allowing to obtain predictions for differential cross-sections with NLO QCD accuracy matched to the accuracy of the Shower Monte Carlo event generator. Effects of non-diagonal CKM matrix elements, finite charm quark mass and off-shell $W$ decays including spin correlations are taken into account. We investigate the production of a leptonically decaying $W$ boson in association with either a charmed meson ($W^\pm~+~D^{*\mp}$) or a charmed jet ($W^\pm~+~j_{c}$) and compare our predictions with particle-level measurements by the ATLAS and CMS collaborations at $\sqrt{s} =$ 7 and 13 TeV. Considering the level of agreement between theory predictions and experimental data in the light of present theoretical and experimental uncertainties, our results do not point to the need of extensive modifications of the strange and antistrange distribution functions in the NLO PDF fits that we used, although collider $W + c$ production data have not been included yet in these fits.