Measurement of $$Z/\gamma^* + b$$-jet Production Cross section in $$p\bar{p}$$ collisions at $$\sqrt{s}= 1.96$$ TeV with the CDF detector
- Univ. Autonoma de Barcelona (Spain). Inst. Catalana de Recerca i Estudis Avancats (ICREA) and Inst. de Fisica d'Altes Energies (IFAE)
Processes at hadron colliders, such as the production of jets, are described by the Quantum Chromodynamics theory (QCD). Precise descriptions of processes involving jets in association with a vector boson have nowadays large relevance as they represent irreducible background to other Standard Model (SM) processes and searches for new physics. The experimental study and understanding of the b-jet production in association with a Z boson are crucial for many reasons. For one side, it is the most important background for a light Higgs boson decaying into a bottom-antibottom quark pair and produced in the ZH mode.This is one of the most promising channels for the Higgs search at Tevatron in particular since the latest results have excluded the high mass region (MH > 127 GeV/c2 ). For another side the signature of b-jets and a Z boson is also background to new physics searches, such as supersymmetry, where a large coupling of the Higgs boson to bottom quarks is allowed. The produ ction cross section measurement of b-jets in events with a Z boson has already been performed at hadron colliders, at the Tevatron by CDF and D0 experiments and are now pursued at the LHC by ATLAS and CMS. In particular the CDF measurement was performed with only 2 fb-1 and was limited by the statistical uncertainty. This PhD thesis presents a new measurement of the $$Z/\gamma^* + b$$-jet production cross section using the complete dataset collected by CDF during the Run II. $$Z/\gamma^*$$ bosons are selected in the electron and muon decay modes and are required to have 66 < MZ < 116 GeV/c2 while jets, reconstructed with the MidPoint algorithm, have to be central (|Y| < 1.5) with pT > 20 GeV/c . The per jet cross section is measured with respect to the $$Z/\gamma^*$$ inclusive and the $$Z/\gamma^* +$$ jets cross sections. Results are compared to leading order (LO) event generator plus parton shower and next-to-leading order (NLO) predictions corrected for non perturbative effects such as hadronizat ion and underlying event. Differential distributions as a fu! nction of jet transverse moment and jet rapidity are also presented together with the comparison to NLO pQCD predictions for different renormalization and factorization scales and various PDF sets.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1247709
- Report Number(s):
- FERMILAB-THESIS-2012-15; 1128177
- Country of Publication:
- United States
- Language:
- English
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