The inclusive top-quark pair () production cross-section was measured in proton-proton collisions at a center of mass energy of 5 TeV with 257 pb of data collected by the ATLAS detector. The cross-section measurement at a lower center of mass helps to further constrain the gluon Parton Distribution Function (PDF) at high Bjorken . The cross-section is first measured individually in both the dilepton and single-lepton channels of the decay before being combined. The measurement in the dilepton channel is measured using a “cut-and-count” approach whereas the single-lepton measurement utilizes a Boosted Decision Tree (BDT) trained on Monte Carlo to separate signal from background. The output distribution of the BDT is the fit to data in a profile-likelihood fit leading to the single-lepton measurement being the most precise single measurement of the cross-section. The combined cross-section improves this measurement by an additional 10%. The results are used to further constrain PDFs at 5 TeV center-of-mass energy.
Authors
Francesco Giuli(CERN)Leonid Serkin(INFN Gruppo Collegato di Udine and ICTP Trieste (IT))Sahibjeet Singh(University of Toronto (CA))Mohammad Kareem(York University (CA))Pekka Sinervo(University of Toronto (CA))Richard Hawkings(CERN)