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Title: Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF

Abstract

We present a new method of measuring the ratio of W and Z production and de- cay (R) at the CDF experiment. We analyze 307 pb -1 of proton-antiproton collisions at the Fermilab Tevatron center-of-mass energy of 1.96 TeV. A single sample containing both W and Z boson candidates is selected by requiring at least one high-energy electron in an event with low hadronic activity. We estimate that less than one percent of our sample is made up of background events after a cut on the recoil energy. A maximum likelihood fits is performed on the missing transverse energy spectrum of the events to determine the relative rates of W and Z production in the common sample. This ratio is defined as: R = Z · → Z Γ(W → £ν) 1 Γ(W ) Br(Z → ££) We have obtained the fi result using this method for the electron channel. R = 10.55 ± 0.09(stat) ± 0.12(syst) We then extract the Branching Ratio of W → £ν using the Branching Ratio of Z → £+£- measured at LEP and a theoretical value for the ratio of the cross sections. σZ Br(W → £ν) = R · W Br(Z → £+more » £-) = 0.1054 ± 0.0016 We also obtain an indirect measurement of the W width of Γtot = 2148 ± 32 MeV. This width gives us information about all the possible decays of the W boson. The W width also constrains the sum of the CKM elements involved in W decays. We find the following value for V cs , the least constrained element: |V cs | = 1.008 ± 0.029.« less

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 Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1415800
Report Number(s):
FERMILAB-THESIS-2007-83; AAT-3276123; PROQUEST-1490074231
842149
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Copic, Katherine Ann. Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF. United States: N. p., 2007. Web. doi:10.2172/1415800.
Copic, Katherine Ann. Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF. United States. doi:10.2172/1415800.
Copic, Katherine Ann. Thu . "Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF". United States. doi:10.2172/1415800. https://www.osti.gov/servlets/purl/1415800.
@article{osti_1415800,
title = {Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF},
author = {Copic, Katherine Ann},
abstractNote = {We present a new method of measuring the ratio of W and Z production and de- cay (R) at the CDF experiment. We analyze 307 pb-1 of proton-antiproton collisions at the Fermilab Tevatron center-of-mass energy of 1.96 TeV. A single sample containing both W and Z boson candidates is selected by requiring at least one high-energy electron in an event with low hadronic activity. We estimate that less than one percent of our sample is made up of background events after a cut on the recoil energy. A maximum likelihood fits is performed on the missing transverse energy spectrum of the events to determine the relative rates of W and Z production in the common sample. This ratio is defined as: R = Z · → Z Γ(W → £ν) 1 Γ(W ) Br(Z → ££) We have obtained the fi result using this method for the electron channel. R = 10.55 ± 0.09(stat) ± 0.12(syst) We then extract the Branching Ratio of W → £ν using the Branching Ratio of Z → £+£- measured at LEP and a theoretical value for the ratio of the cross sections. σZ Br(W → £ν) = R · W Br(Z → £+ £-) = 0.1054 ± 0.0016 We also obtain an indirect measurement of the W width of Γtot = 2148 ± 32 MeV. This width gives us information about all the possible decays of the W boson. The W width also constrains the sum of the CKM elements involved in W decays. We find the following value for Vcs , the least constrained element: |Vcs | = 1.008 ± 0.029.},
doi = {10.2172/1415800},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}

Thesis/Dissertation:
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