Measurement of the Associated $\gamma + \mu^\pm$ Production Cross Section in $p \bar p$ Collisions at $\sqrt{s} = 1.8$ TeV

TL;DR

This paper reports the first measurement of the associated gamma and muon production cross section in proton-antiproton collisions at 1.8 TeV, providing insights into charm quark content and testing QCD predictions.

Contribution

It presents the first experimental measurement of gamma + muon production in hadronic collisions and compares it with QCD models, probing charm quark distributions.

Findings

Measured cross section: 29 ± 9 pb^{-1}

Agreement with QCD models within uncertainties

Sensitive to charm quark content of the proton

Abstract

We present the first measurement of associated direct photon + muon production in hadronic collisions, from a sample of 1.8 TeV $p \bar p$ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from the Compton scattering process $cg \to c\gamma$, with the final state charm quark producing a muon. Hence this measurement is sensitive to the charm quark content of the proton. The measured cross section of $29\pm 9 pb^{-1}$ is compared to a leading-order QCD parton shower model as well as a next-to-leading-order QCD calculation.