Dijet Production in √s̅ = 7 TeV pp Collisions with Large Rapidity Gaps at the ATLAS Experiment

A 6.8 nb⁻¹ sample of pp collision data collected under low-luminosity conditions at √s̅ = 7 TeV by the ATLAS detector at the Large Hadron Collider is used to study diffractive dijet production. Events containing at least two jets with p{T} > 20 GeV are selected and analysed in terms of variables which discriminate between diffractive and non-diffractive processes. Cross sections are measured differentially in Δη^F, the size of the observable forward region of pseudorapidity which is devoid of hadronic activity, and in an estimator, ξ̃, of the fractional momentum loss of the proton assuming single diffractive dissociation (pp → pX). Model comparisons indicate a dominant non-diffractive contribution up to moderately large Δη^F and small ξ̃, with a diffractive contribution which is significant at the highest Δη^F and the lowest ξ̃. The rapidity-gap survival probability is estimated from comparisons of the data in this latter region with predictions based on diffractive parton distribution functions.