Measurement of the Cross Section for Prompt Diphoton Production in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report a measurement of the rate of prompt diphoton production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using a data sample of $207{\mathrm{pb}}^{-1}$ collected with the upgraded Collider Detector at Fermilab. The background from nonprompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.

Figure 1

The $\gamma \gamma$ mass distribution from the CDF Run II data, along with predictions from diphox (solid line), resbos (dashed line), and pythia (dot-dashed line). The pythia predictions have been scaled by a factor of 2. The inset shows, on a linear scale, the total $\gamma \gamma$ cross section in diphox with (solid line)/without (dashed line) the $gg$ contribution.

Figure 2

The $\gamma \gamma$ $q_T$ distribution from the CDF Run II data, along with predictions from diphox (solid line), resbos (dashed line), and pythia (dot-dashed line). The pythia predictions have been scaled by a factor of 2. Also shown, at larger $q_T$, are the diphox prediction (dotted line) and the CDF Run II data (open squares: shifted to the right by 1 GeV for visibility) for the configuration where the two photons are required to have $\Delta \varphi <\pi /2$.

Figure 3

The $\Delta \varphi$ angle between the two photons from the CDF Run II data, along with predictions from diphox (solid line), resbos (dashed line), and pythia (dot-dashed line). The pythia predictions have been scaled by a factor of 2.