Abstract
Abstract The inclusive b-jet production cross section in pp collisions at a center-of mass energy of 7 TeV is measured using data collected by the CMS experiment at the LHC. The cross section is presented as a function of the jet transverse momentum in the range 18 < p T < 200 GeV for several rapidity intervals. The results are also given as the ratio of the b-jet production cross section to the inclusive jet production cross section. The measurement is performed with two different analyses, which differ in their trigger selection and b-jet identification: a jet analysis that selects events with a b jet using a sample corresponding to an integrated luminosity of 34 pb−1, and a muon analysis requiring abjetwithamuonbasedonanintegratedluminosityof3pb−1. Inbothapproachestheb jets are identified by requiring a secondary vertex. The results from the two methods are in agreement with each other and with next-to-leading order calculations, as well as with predictions based on the pythia event generator.
Highlights
The inclusive b-jet production cross section in pp collisions at a center-ofmass energy of 7 TeV is measured using data collected by the Compact Muon Solenoid (CMS) experiment at the LHC
The measurement is performed with two different analyses, which differ in their trigger selection and b-jet identification: a jet analysis that selects events with a b jet using a sample corresponding to an integrated luminosity of 34 pb−1, and a muon analysis requiring a b jet with a muon based on an integrated luminosity of 3 pb−1
√ First results on bb production in pp collisions at s = 7 TeV have been reported by the LHCb Collaboration using semi-inclusive decays in the forward rapidity region [14], and by the Compact Muon Solenoid (CMS) Collaboration [15] using inclusive b → μX decays [16] in the central rapidity region and measuring the b-hadron production cross section as a function of the muon transverse momentum and pseudorapidity
Summary
The central feature of the CMS apparatus is a superconducting solenoid, 13 m in length and 6 m in diameter, which provides an axial magnetic field of 3.8 T. The bore of the solenoid is instrumented with various particle detectors. Charged particle trajectories are measured with the silicon pixel and strip trackers, covering 0 < φ < 2π in azimuth and |η| < 2.5 in pseudorapidity, where η = − ln[tan θ/2], with θ being the polar angle of the track with respect to the counterclockwise beam direction. The resolution is typically about 15 μm on the impact parameter and about 1% on the transverse momentum for charged particles with pT < 40 GeV. The forward region is covered by a an iron/quartz-fiber hadron calorimeter (HF). The ECAL has an energy resolution of better than 0.5% for unconverted photons with transverse energies above 100 Ge√V. The hadron calorimeters cover |η| < 5.0 with a jet energy resolution of about 100%/ E, with the jet energy E in GeV. A more detailed description of the CMS detector can be found elsewhere [15]
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