Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV

Abstract

The cross section for the inclusive production of isolated photons has been measured in p anti-p collisions at sqrt{s}=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity |eta|<0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.

Figures (5)

• Figure 1: Normalized distributions of NN output ($O_{\rm NN}$) in $Z\rightarrow e^+e^-$ events for data ($\bullet$) and MC ($\circ$).
• Figure 2: Distribution of the number of events in data ($\bullet$) as a function of the NN output ($O_{\rm NN}$) for $44<p_T^\gamma<50$ GeV. The contributions from MC background ($\circ$) and summed MC signal and background ($_{^\Box}$) are also shown. The MC points were weighted according to the fitted purity (the errors shown are statistical).
• Figure 3: Dependence of the photon purity on $p_T^\gamma$. The dashed line represents a fit to these points, the filled area corresponds to the statistical uncertainty band, and the solid lines to the total uncertainty band. The NN output in data was fit to the shapes of the MC signal and background samples.
• Figure 4: The inclusive cross section for the production of isolated photons as a function of $p_T^\gamma$. The results from the NLO pQCD calculation with jetphox are shown as solid line.
• Figure 5: The ratio of the measured cross section to the theoretical predictions from jetphox. The full vertical lines correspond to the overall uncertainty while the internal line indicates just the statistical uncertainty. Dashed lines represents the change in the cross section when varying the theoretical scales by factors of two. The shaded region indicates the uncertainty in the cross section estimated with CTEQ6.1 PDFs.