Measurements of the Ratio of W and Z Production and the W Boson Decay Width at CDF
- Univ. of Michigan, Ann Arbor, MI (United States)
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.
- 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:
- 1415800
- Report Number(s):
- FERMILAB-THESIS-2007-83; AAT-3276123; PROQUEST-1490074231; 842149
- Country of Publication:
- United States
- Language:
- English
Similar Records
Measurement of W and Z boson production and extraction of the W width and branching ratios at CDF
Measurement of the absolute branching fractions for purely leptonic decays