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A Study of W Boson Properties with Four-Jet W⁺W⁻ Events at LEP


Shvorob, Alexander (2001) A Study of W Boson Properties with Four-Jet W⁺W⁻ Events at LEP. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/5drh-kh53.


In this thesis I present a study of W pair production in e+e- annihilation using fully hadronic W+W- events. Data collected by the L3 detector at LEP in 1996-1998, at collision center-of-mass energies between 161 and 189 GeV, was used in my analysis.

Analysis of the total and differential W+W- cross sections with the resulting sample of 1,932 W+W- → qqqq event candidates allowed me to make precision measurements of a number of properties of the W boson. I combined my measurements with those using other W+W- final states to obtain stringent constraints on the W boson's couplings to fermions, other gauge bosons, and scalar Higgs field by measuring the total e+e- → W+W- cross section and its energy dependence

σ(e+e- → W+W-) =

{2.68+0.98-0.67(stat.)± 0.14(syst.) pb, √s = 161.34 GeV

{12.04+1.38-1.29(stat.)± 0.23(syst.) pb, √s = 172.13 GeV

{16.45 ± 0.67(stat.) ± 0.26(syst.) pb, √s = 182.68 GeV

{16.28 ± 0.38(stat.) ± 0.26(syst.) pb, √s = 188.64 GeV

the fraction of W bosons decaying into hadrons

BR(W →qq') = 68.72 ± 0.69(stat.) ± 0.38(syst.) %,

invisible non-SM width of the W boson

ΓinvisibleW less than MeV at 95% C.L.,

the mass of the W boson

MW = 80.44 ± 0.08(stat.)± 0.06(syst.) GeV,

the total width of the W boson

ΓW = 2.18 ± 0.20(stat.)± 0.11(syst.) GeV,

the anomalous triple gauge boson couplings of the W

ΔgZ1 = 0.16+0.13-0.20(stat.) ± 0.11(syst.)

Δkγ = 0.26+0.24-0.33(stat.) ± 0.16(syst.)

λγ = 0.18+0.13-0.20(stat.) ± 0.11(syst.)

No significant deviations from Standard Model predictions were found in any of the measurements.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Newman, Harvey B.
Thesis Committee:
  • Newman, Harvey B. (chair)
  • Hughes, Emlyn Willard
  • Weinstein, Alan Jay
  • Wise, Mark B.
Defense Date:8 September 2000
Record Number:CaltechTHESIS:07292014-091223849
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8619
Deposited By: Benjamin Perez
Deposited On:29 Jul 2014 18:18
Last Modified:12 Sep 2022 23:15

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