Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions root s=13TeV with the ATLAS detector

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2017, Vol.77 (4)
• Main Authors: Aaboud, M, Kastanas, Konstatinos A., Lund-Jensen, Bengt, Sidebo, P. Edvin, Strandberg, Jonas, Zwalinski, L, et al
• Format: Article
• Language: English
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-017-4766-0

Measurements of jet activity in top-quark pair events produced in proton–proton collisions are presented, using 3.2 fb - 1 of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge eμ pair and two b-tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, p T . The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as a function of the p T threshold for additional jets, and is also presented for different invariant mass regions of the eμbb¯ system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.