Abstract
The dijet production cross section for jets containing a b-hadron (b-jets) has been measured in proton–proton collisions with a centre-of-mass energy of sqrt{s} = 7 TeV, using the ATLAS detector at the LHC. The data used correspond to an integrated luminosity of mathrm 4.2,text {fb}^{-1}. The cross section is measured for events with two identified b-jets with a transverse momentum p_{text {T}} > 20 GeV and a minimum separation in the eta –phi plane of Delta R = 0.4. At least one of the jets in the event is required to have p_{text {T}} > 270 GeV. The cross section is measured differentially as a function of dijet invariant mass, dijet transverse momentum, boost of the dijet system, and the rapidity difference, azimuthal angle and angular distance between the b-jets. The results are compared to different predictions of leading order and next-to-leading order perturbative quantum chromodynamics matrix elements supplemented with models for parton-showers and hadronization.
Highlights
The dijet production cross section for jets containing proton a b-hadron (b-jets) has been measured collisions with a centre-of-mass energy inofp√roston=
The differential cross section for bbproduction is shown as a function of the six observables in Figs. 3, 4, 5, 6, 7, 8
The middle and lower panels report the ratio of theoretical predictions to data
Summary
The ATLAS detector [12] consists of an inner tracking system, immersed in a 2 T axial magnetic field, surrounded by electromagnetic calorimeters, hadronic calorimeters and a muon spectrometer. The hadronic end-cap calorimeter uses liquid argon with copper absorber plates and extends up to |η| = 3.2. The outer region of the detector is formed by a muon spectrometer that uses a toroidal magnetic field with a bending power of 1.5–5.5 Tm in the barrel and 1.0–7.5 Tm in the end-caps. The trigger system uses three consecutive levels to record a selection of interesting events. The jet triggers at L1 use information about the energy deposits in the electromagnetic and hadronic calorimeters using trigger towers with a granularity of φ × η = 0.1 × 0.1. The factor by which the number of events that pass a trigger is reduced is known as the prescale
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