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Title: Measurement of the W ± + b$$\bar{b}$$ cross-section in 695-pb -1 of p$$\bar{p}$$ collisions at CDF II.

Abstract

W ± + b$$\bar{b}$$ events contain the associated production of a W ± boson, a pair of bottom quarks (b$$\bar{b}$$), and any number of additional partons. This process is of much importance at hadron collider experiments due to its role as a background source in searches for Standard Model Higgs boson and single top-quark production. In this thesis the results are presented for a measurement of the b-jet cross-section in W ± + b$$\bar{b}$$ events containing 1 or 2 jets in 695 pb -1 of √s =1.96 TeV p$$\bar{p}$$ collisions at the CDF experiment. This is the first measurement of the cross-section of W ± b$$\bar{b}$$ performed in any experiment. The cross-section is defined to be proportional to the number of b-jets from W ± b$$\bar{b}$$ events with one or two jets, and a leptonically decaying W ± with decay products passing kinematics cuts (p T(ℓ ±) ≥ 20.0 GeV, |η(ℓ ±)| ≤ 1.1, p T(v) ≥ 25.0 GeV). The invariant mass distribution of jets identified as containing a long-lived hadron is fit with components for bottom, charm, and light-flavor to find the fraction due to true b-decays. Background b-jet sources are subtracted to isolate the contribution of W ± b$$\bar{b}$$ to the data. The cross-section is measured to be 0.90 ± 0.20(stat.) ± 0.26(syst.)pb, which compares well with the leading order theoretical prediction of 0.74 ± 0.18 pb.

Authors:
 [1]
  1. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
923523
Report Number(s):
FERMILAB-THESIS-2006-59
TRN: US0801858
DOE Contract Number:
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DAUGHTER PRODUCTS; FERMILAB COLLIDER DETECTOR; FORECASTING; HADRONS; HIGGS BOSONS; MASS DISTRIBUTION; PRODUCTION; QUARKS; STANDARD MODEL; Experiment-HEP

Citation Formats

Soderberg, Mitchell Paul. Measurement of the W± + b$\bar{b}$ cross-section in 695-pb-1 of p$\bar{p}$ collisions at CDF II.. United States: N. p., 2006. Web. doi:10.2172/923523.
Soderberg, Mitchell Paul. Measurement of the W± + b$\bar{b}$ cross-section in 695-pb-1 of p$\bar{p}$ collisions at CDF II.. United States. doi:10.2172/923523.
Soderberg, Mitchell Paul. Sun . "Measurement of the W± + b$\bar{b}$ cross-section in 695-pb-1 of p$\bar{p}$ collisions at CDF II.". United States. doi:10.2172/923523. https://www.osti.gov/servlets/purl/923523.
@article{osti_923523,
title = {Measurement of the W± + b$\bar{b}$ cross-section in 695-pb-1 of p$\bar{p}$ collisions at CDF II.},
author = {Soderberg, Mitchell Paul},
abstractNote = {W± + b$\bar{b}$ events contain the associated production of a W± boson, a pair of bottom quarks (b$\bar{b}$), and any number of additional partons. This process is of much importance at hadron collider experiments due to its role as a background source in searches for Standard Model Higgs boson and single top-quark production. In this thesis the results are presented for a measurement of the b-jet cross-section in W± + b$\bar{b}$ events containing 1 or 2 jets in 695 pb-1 of √s =1.96 TeV p$\bar{p}$ collisions at the CDF experiment. This is the first measurement of the cross-section of W± b$\bar{b}$ performed in any experiment. The cross-section is defined to be proportional to the number of b-jets from W± b$\bar{b}$ events with one or two jets, and a leptonically decaying W± with decay products passing kinematics cuts (pT(ℓ±) ≥ 20.0 GeV, |η(ℓ±)| ≤ 1.1, pT(v) ≥ 25.0 GeV). The invariant mass distribution of jets identified as containing a long-lived hadron is fit with components for bottom, charm, and light-flavor to find the fraction due to true b-decays. Background b-jet sources are subtracted to isolate the contribution of W± b$\bar{b}$ to the data. The cross-section is measured to be 0.90 ± 0.20(stat.) ± 0.26(syst.)pb, which compares well with the leading order theoretical prediction of 0.74 ± 0.18 pb.},
doi = {10.2172/923523},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

Thesis/Dissertation:
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  • In this thesis the measurements of differential cross sections for the production of themore » $W$-boson in association with jets in $$p\bar{p}$$ collisions at $$\sqrt{s} = 1.96$$ TeV are presented. The measurements are based on 9.0 fb$$^{-1}$$ of CDF Run II data (i.e., the full dataset). Only events in which the W-boson decays leptonically (i.e., W → ev and W → μv)and at least one jet is present are considered. The lepton candidates are required to have a transverse energy $$E^{\ell}_T > 25$$GeV and pseudorapidity in the range |n | < 1 whereas, the jets are reconstructed using the JETCLU algorithm with a radius of 0.4 requiring transverse energy $$E^{jet}_T > 25$$GeV and pseudorapidity in the range |η jet| < 2. The reconstructed W-boson transverse mass should be greater than 40GeV/c 2. The differential cross sections as a function of the jet multiplicity ($N$ > or = to 1, 2, 3, 4) and the leading jet transverse energy, are measured separately for each decay channel and then combined. For a meaningful comparison with theory the measured cross-sections are unfolded to remove detector effects. The resulting particle-level cross-sections are compared to theoretical predictions.« less
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