Measurement of the muon charge asymmetry in ppbar to W + X to mu nu + X events at sqrt{s} = 1.96 TeV

TL;DR

This paper measures the muon charge asymmetry from W boson decays at the Fermilab Tevatron, comparing results with theoretical predictions and highlighting discrepancies at higher transverse momentum and pseudorapidity.

Contribution

It provides the first detailed measurement of muon charge asymmetry in specific kinematic regions at sqrt{s} = 1.96 TeV, testing parton distribution functions against experimental data.

Findings

Predicted asymmetries do not match data at high pT and eta.

Discrepancies suggest need for improved parton distribution functions.

Results constrain models of proton structure.

Abstract

We present a measurement of the muon charge asymmetry from the decay of the $W$ boson via W to mu nu using 7.3 fb^{-1} of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider at sqrt{s} = 1.96 TeV. The muon charge asymmetry is presented in two kinematic regions in muon transverse momentum and event missing transverse energy: (p^{\mu}_{T} > 25 GeV, \met > 25 GeV) and (p^{\mu}_{T} > 35 GeV, \met > 35 GeV). The measured asymmetries are compared with theory predictions made using three parton distribution function sets. The predictions do not describe the data well for p^{\mu}_{T} > 35 GeV, \met > 35 GeV, and larger values of muon pseudorapidity.