Measurement of the γ + D^{* ±} Cross Section in pp Collisions at √ s = 1.8 TeV

We have measured the cross section of γ + D^{* ±} production in pp collisions at √ = 1.8 TeV using the Collider Detector at Fermilab. In this kinematic region, the Compton scattering process (g_c → γ c) is expected to dominate and thus provide a direct link to the charm quark density in the proton. From the 45 ± 18 γ + D^{* ±} candidates in a 16.4 pb^{− 1} data sample, we have determined the production cross section to be 0.38 ± 0.15 ± (stat) ± 0.11(syst)nb for the rapidity range | y(D^{* ±})| < 1.2 and | y (γ) | < 0.9, and for the transverse momentum range pT(D^{* ±}) > 6GeV/c and 16 < pT(γ) < 40 GeV/c. The measured cross section is compared to a theoretical prediction.