Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron

TL;DR

This paper measures the diffractive structure function of the antiproton in proton-antiproton collisions at two energies, compares the results with QCD predictions, and explores the dependence on kinematic variables, providing insights into diffraction at high energies.

Contribution

It presents the first detailed measurement of the diffractive structure function at two different energies and tests QCD factorization in diffractive dijet production.

Findings

The ratio of $F_{jj}^D$ at 630 GeV to 1800 GeV is compared with QCD expectations.

$F_{jj}^D$ exhibits a $eta^{-1.0 ext{ to }-1.1}$ and $\xi^{-0.9 ext{ to }-1.0}$ dependence, indicating $eta$-$\xi$ factorization.

The measured dependence supports certain theoretical models of diffraction at high energies.

Abstract

We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=1800$ GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the $\xi$ ($x$-Pomeron) and $\beta$ ($x$ of parton in Pomeron) dependence of $F_{jj}^D$ at $\sqrt s=1800$ GeV. In the region $0.035<\xi<0.095$, $|t|<1$ GeV$^2$ and $\beta<0.5$, $F_{jj}^D(\beta,\xi)$ is found to be of the form $\beta^{-1.0\pm 0.1} \xi^{-0.9\pm 0.1}$, which obeys $\beta$-$\xi$ factorization.