Measurement of jet activity in top quark events using the eµ final state with two b-tagged jets in pp collisions at √s = 8 TeV with the ATLAS detector

Aaboud, M; Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Abeloos, B; Aben, R; AbouZeid, O S; Abraham, N L; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Affolder, A A; Agatonovic-Jovin, T; Agricola, J; 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

Measurement of jet activity in top quark events using the eµ final state with two b-tagged jets in pp collisions at √s = 8 TeV with the ATLAS detector

Journal Article

2016

Journal Title

Journal of High Energy Physics

Link to Journal

https://dx.doi.org/10.1007/JHEP09(2016)074

Department

Department of Physics

Faculty

Faculty of Science

Abstract

Measurements of the jet activity in tt¯ events produced in proton-proton collisions at √ s = 8 TeV are presented, using 20.3 fb−1 of data collected by the ATLAS experiment at the Large Hadron Collider. The events were selected in the dilepton eµ decay channel with two identified b-jets. The numbers of additional jets for various jet transverse momentum (pT) thresholds, and the normalised differential cross-sections as a function of pT for the five highest-pT additional jets, were measured in the jet pseudorapidity range |η| < 4.5. The gap fraction, the fraction of events which do not contain an additional jet in a central rapidity region, was measured for several rapidity intervals as a function of the minimum pT of a single jet or the scalar sum of pT of all additional jets. These fractions were also measured in different intervals of the invariant mass of the eµb¯b system. All measurements were corrected for detector effects, and found to be mostly well-described by predictions from next-to-leading-order and leading-order tt¯ event generators with appropriate parameter choices. The results can be used to further optimise the parameters used in such generators.