Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with QuasiMonte Carlo integration
Abstract
This thesis presents a measurement of the top quark mass obtained from p$$\bar{p}$$ collisions at √s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. The measurement uses a matrix element integration method to calculate a t$$\bar{t}$$ likelihood, employing a QuasiMonte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a t$$\bar{t}$$ likelihood as a 2D function of the top pole mass m _{t} and Δ _{JES}, where Δ _{JES} parameterizes the uncertainty in our knowledge of the jet energy scale; it is a shift applied to all jet energies in units of the jetdependent systematic error. By introducing Δ _{JES} into the likelihood, we can use the information contained in W boson decays to constrain Δ _{JES} and reduce error due to this uncertainty. We use a neural network discriminant to identify events likely to be background, and apply a cut on the peak value of individual event likelihoods to reduce the effect of badly reconstructed events. This measurement uses a total of 4.3 fb ^{1} of integrated luminosity, requiring events with a lepton, large E _{T}, and exactly four highenergy jets in the pseudorapidity range η < 2.0, of which at least one must be tagged as coming from a b quark. In total, we observe 738 events before and 630 events after applying the likelihood cut, and measure m _{t} = 172.6 ± 0.9 (stat.) ± 0.7 (JES) ± 1.1 (syst.) GeV/c ^{2}, or m _{t} = 172.6 ± 1.6 (tot.) GeV/c ^{2}.
 Authors:
 Univ. of California, Berkeley, CA (United States)
 Publication Date:
 Research Org.:
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 963775
 Report Number(s):
 FERMILABTHESIS200926
TRN: US0903275
 DOE Contract Number:
 AC0207CH11359
 Resource Type:
 Thesis/Dissertation
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; B QUARKS; FERMILAB COLLIDER DETECTOR; FERMILAB TEVATRON; INTERMEDIATE BOSONS; LEPTONS; LUMINOSITY; MATRIX ELEMENTS; NEURAL NETWORKS; QUARKS; RESOLUTION; T QUARKS; ExperimentHEP
Citation Formats
Lujan, Paul Joseph. Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with QuasiMonte Carlo integration. United States: N. p., 2009.
Web. doi:10.2172/963775.
Lujan, Paul Joseph. Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with QuasiMonte Carlo integration. United States. doi:10.2172/963775.
Lujan, Paul Joseph. 2009.
"Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with QuasiMonte Carlo integration". United States.
doi:10.2172/963775. https://www.osti.gov/servlets/purl/963775.
@article{osti_963775,
title = {Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with QuasiMonte Carlo integration},
author = {Lujan, Paul Joseph},
abstractNote = {This thesis presents a measurement of the top quark mass obtained from p$\bar{p}$ collisions at √s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. The measurement uses a matrix element integration method to calculate a t$\bar{t}$ likelihood, employing a QuasiMonte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a t$\bar{t}$ likelihood as a 2D function of the top pole mass mt and ΔJES, where ΔJES parameterizes the uncertainty in our knowledge of the jet energy scale; it is a shift applied to all jet energies in units of the jetdependent systematic error. By introducing ΔJES into the likelihood, we can use the information contained in W boson decays to constrain ΔJES and reduce error due to this uncertainty. We use a neural network discriminant to identify events likely to be background, and apply a cut on the peak value of individual event likelihoods to reduce the effect of badly reconstructed events. This measurement uses a total of 4.3 fb1 of integrated luminosity, requiring events with a lepton, large ET, and exactly four highenergy jets in the pseudorapidity range η < 2.0, of which at least one must be tagged as coming from a b quark. In total, we observe 738 events before and 630 events after applying the likelihood cut, and measure mt = 172.6 ± 0.9 (stat.) ± 0.7 (JES) ± 1.1 (syst.) GeV/c2, or mt = 172.6 ± 1.6 (tot.) GeV/c2.},
doi = {10.2172/963775},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2009,
month =
}

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