Measurement of b-bbar correlations at the LHC with ATLAS

The Large Hadron Collider at CERN will produce b-hadrons with very high statistics, and with a higher energy reach than any previous machine. The ATLAS detector will offer excellent acceptance and performance for b physics studies and will make high statistics measurements of b-quark production to probe QCD. ATLAS can contribute to the measurement of the absolute and differential production cross-sections. Measurements of b-bbar correlations will be made to test the NLO contributions to the cross-section and to place limits on non-perturbative effects. A novel technique is presented where one b quark direction is measured through the reconstruction of a J/Psi meson, and the other via its semi-leptonic decay to a muon. This technique potentially represents a considerable improvement on previous measurements that have used dimuon samples, where backgrounds are much higher and the presence of resonant decays to two muons demand the application of cuts on the muon-muon opening angle or invariant mass.