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

F. MONTICELLI; ATLAS

JOURNAL OF HIGH ENERGY PHYSICS

SPRINGER

Lugar: Berlin; Año: 2016

1126-6708

Measurements of the jet activity in t t  ̄ 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 theLarge Hadron Collider. The events were selected in the dilepton eμ decay channel withtwo identified b-jets. The numbers of additional jets for various jet transverse momentum(p T ) thresholds, and the normalised differential cross-sections as a function of p T for the fivehighest-p T additional jets, were measured in the jet pseudorapidity range |η| < 4.5. The gapfraction, the fraction of events which do not contain an additional jet in a central rapidity re-gion, was measured for several rapidity intervals as a function of the minimum p T of a singlejet or the scalar sum of p T of all additional jets. These fractions were also measured in differ-ent intervals of the invariant mass of the eμbb̄ system. All measurements were corrected fordetector effects, and found to be mostly well-described by predictions from next-to-leading-order and leading-order t t  ̄ event generators with appropriate parameter choices. The resultscan be used to further optimise the parameters used in such generators.