Measurement of the associated $\gamma +{\mu }^{\pm }$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}$ TeV

We present the first measurement of associated direct photon$+$muon production in hadronic collisions, from a sample of 1.8 TeV $p\overline{p}$ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from the Compton scattering process $c\overrightarrow{g}c\gamma ,$ 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 is compared to a leading-order QCD parton shower model as well as a next-to-leading-order QCD calculation.