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Two b or not two b-jets : measurements of inclusive and dijet b-jet differential cross-sections with the ATLAS detector

This thesis discusses the measurement of the inclusive b-jet cross-section using the 2010 ATLAS dataset and the measurement of di-b-jet cross-sections using the 2011 dataset. The inclusive b-jet analysis measured the pT spectrum of b-jets in the range 20<pT<400 GeV in four rapidity ranges, |y|<0.3, 0.3 < |y| < 0.8, 0.8 < |y| < 1.2 and 1.2 < |y| < 2.1. Good agreement was observed between data and the NLO theory predictions generated by the POWHEG and MC@NLO Monte Carlo generators. However, when the cross-section measurement was split into the |y| regions, MC@NLO showed some shape differences with respect to data. The di-b-jet analysis using the 2011 ATLAS dataset measured the di-b-jet cross-section with respect to six different variables. This analysis investigates regions of phase space that are sensitive to different bb production mechanisms. It was found that Monte Carlo simulation predicts back- to-back b-jet topologies well. Situations where the b-jets are closer together are more challenging to model and both MC@NLO and POWHEG overpredict the rate of such events.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:594352
Date January 2013
CreatorsBieniek, S. P.
PublisherUniversity College London (University of London)
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://discovery.ucl.ac.uk/1410936/

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