Measurement of the muon charge asymmetry in inclusive $pp \rightarrow W + X$ production at $\sqrt{s} = 7$ TeV at CMS and an improved determination of light parton distribution functions

TL;DR

This paper reports precise measurements of muon charge asymmetry in proton-proton collisions at 7 TeV, providing new constraints on proton parton distribution functions through a combined analysis with HERA data.

Contribution

It presents the most precise muon charge asymmetry measurements at 7 TeV and improves the determination of light parton distribution functions using a combined QCD analysis.

Findings

Enhanced statistical precision over previous measurements

Provides new constraints on proton parton distribution functions

Improves understanding of proton structure in the Bjorken x range 10^{-3} to 10^{-1}

Abstract

Measurements of the muon charge asymmetry in inclusive $pp \rightarrow WX$ production at $\sqrt{s}=7$ TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 $\mathrm{fb^{-1}}$ recorded with the CMS detector at the LHC. With a sample of more than twenty million $W \rightarrow \mu\nu$ events, the statistical precision is greatly improved in comparison to previous measurements. These new results provide additional constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable $x$ from $10^{-3}$ to $10^{-1}$. These measurements are used together with the cross sections for inclusive deep inelastic ep scattering at HERA in a next-to-leading-order QCD analysis.