A measurement of the Z{sup 0} hadronic branching fraction to bottom quarks and the charged multiplicity of bottom quark events using precision vertex detectors at E{sub cm} = 91 GeV

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Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z{degree} decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z{degree} decays which produce b{bar b} events, F{sub b}. It ... continued below

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296 p.

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Koetke, D. S. June 1, 1992.

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Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z{degree} decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z{degree} decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub {minus}0.045}{sup +0.053} (stat) {sub {minus}0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z{degree} decays, {delta}{bar n}{sub b} = 2.11 {plus_minus} 1.82(stat) {plus_minus} 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 {plus_minus} 1.82 (stat) {plus_minus} 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 {plus_minus} 1.82 (stat) {plus_minus} 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.

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296 p.

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OSTI; NTIS; INIS; GPO Dep.

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  • Other Information: TH: Thesis (Ph.D.)

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  • Other: DE92018236
  • Report No.: SLAC--396
  • Grant Number: AC03-76SF00515
  • DOI: 10.2172/10164831 | External Link
  • Office of Scientific & Technical Information Report Number: 10164831
  • Archival Resource Key: ark:/67531/metadc1389493

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  • June 1, 1992

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  • Nov. 28, 2018, 2:33 p.m.

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  • Dec. 11, 2018, 1:37 p.m.

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Koetke, D. S. A measurement of the Z{sup 0} hadronic branching fraction to bottom quarks and the charged multiplicity of bottom quark events using precision vertex detectors at E{sub cm} = 91 GeV, thesis or dissertation, June 1, 1992; Menlo Park, California. (digital.library.unt.edu/ark:/67531/metadc1389493/: accessed January 19, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.