Production of exclusive dijets in diffractive deep inelastic scattering at HERA

TL;DR

This paper reports on the measurement of exclusive dijet production in diffractive deep inelastic scattering at HERA, analyzing cross sections and energy flows to test various diffractive exchange models.

Contribution

It provides the first detailed measurement of exclusive dijet production as a function of multiple variables, comparing results to different theoretical models of diffractive exchange.

Findings

Cross sections vary with $eta$ and $$

Energy flows around jets are characterized

Results favor certain diffractive exchange models

Abstract

Production of exclusive dijets in diffractive deep inelastic $e^\pm p$ scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb$^{-1}$. The measurement was performed for $\gamma^*-p$ centre-of-mass energies in the range $90 < W < 250$ GeV and for photon virtualities $Q^2 > 25$ GeV$^2$. Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of $\beta$ and $\phi$, where $\beta=x/x_{\rm I\!P}$, $x$ is the Bjorken variable and $x_{\rm I\!P}$ is the proton fractional longitudinal momentum loss. The angle $\phi$ is defined by the $\gamma^*-$dijet plane and the $\gamma^*-e^\pm$ plane in the rest frame of the diffractive final state. The $\phi$ cross section is measured in bins of $\beta$. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.