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 at [Formula: see text] TeV with the ATLAS detector

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2017-04, Vol.77 (4), p.220
• Main Authors: Aaboud, M, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, AbouZeid, O S, Abraham, N L, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, B S, Adachi, S, Adamczyk, L, Adams, D L, Adelman, J, Adomeit, S, Adye, T, Affolder, A A, Agatonovic-Jovin, T, Aguilar-Saavedra, J A, Ahlen, S P, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, T P A, Akimov, A V, Alberghi, G L, Albert, J, Albrand, S, Alconada Verzini, M J, Aleksa, M, Aleksandrov, I N, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Ali, B, Aliev, M, Alimonti, G, Alison, J, Alkire, S P, Allbrooke, B M M, Allen, B W, Allport, P P, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, A A, Alstaty, M, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, M G, Amadio, B T, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, S P, Amorim, A, Amoroso, S, Amundsen, G, Anastopoulos, C, Ancu, L S, Andari, N, Andeen, T, Anders, C F, Anders, J K, Anderson, K J, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Angerami, A, Anghinolfi, F, Anisenkov, A V, Anjos, N, Annovi, A, Antel, C, Antonelli, M, Antonov, A, Antrim, D J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, J P, Arce, A T H, Arduh, F A, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, A J, Armitage, L J, Arnaez, O, Arnold, H, Arratia, M, Arslan, O
• Format: Article
• Language: English
• Subjects: Detection equipment; Measurement
• 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[Formula: see text] of 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 [Formula: see text] pair and two -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, [Formula: see text]. 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 [Formula: see text] threshold for additional jets, and is also presented for different invariant mass regions of the [Formula: see text] 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.