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Category :
Languages : en
Pages : 4

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Longitudinal polarization of the SLC e− beam allows a direct measurement of the left-right, forward-backward asymmetry of c-quarks to be made with the SLD. Events from Z° --> c{bar c} are tagged using fully and partially reconstructed decays of D{sup *+} mesons, and fully reconstructed decays of D mesons. The authors measure A{sub c} = 0.77 " 0.22(stat.) " 0.10(syst.).

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Category :
Languages : en
Pages :

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Category : Aeronautics
Languages : en
Pages : 694

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Category :
Languages : en
Pages : 6

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We present a direct measurement of the parity-violating parameter A{sub b} by analyzing the left-right forward-backward asymmetry of b quarks in ee− --> Z{sup o} --> b{bar b}. The SLD experiment observes hadronic decays of Z{sup o} bosons produced at resonance in collisions of longitudinally polarized electrons and unpolarized positrons at the SLC. Heavy flavor decays of the Z{sup o} are identified by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and precise tracking from SLD. The asymmetry A{sub b} is measured with a self-calibrating technique employing momentum-weighted track charge from both hemispheres in the tagged events. From our 1994--1995 sample of 3.6 pb−1 of ee− annihilation data with a luminosity-weighted average e− polarization of 77.3%, and our 1993 sample of 1.8 pb−1 with a luminosity-weighted polarization of 63.1%, we obtain A{sub b}(preliminary) = 0.843 " 0.046(stat.) " 0.051(syst.).

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Category : Power resources
Languages : en
Pages : 936

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Category : Power resources
Languages : en
Pages : 668

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Category :
Languages : en
Pages : 132

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This thesis presents a direct measurement of the parity-violating parameter A{sub b} by analyzing the polarized forward-backward asymmetry of b quarks in ee− --> Z° --> b{bar b}. Data were taken at the Stanford Linear Accelerator Center (SLAC), with the Stanford Large Detector (SLD), which records the products of ee− interactions at a center of mass energy (square root)s = 91.2 GeV/c2 at the SLAC Linear Collider (SLC). The SLC/SLD experimental apparatus provides a unique and ideal environment for measuring electroweak asymmetries. Heavy flavor decays of the Z° were identified inclusively by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and SLD's precise tracking detectors. Two analysis techniques for measuring A{sub b} are presented: a binned fit to the left-right forward-backwards asymmetry of tagged events signed with momentum-weighted track charge, and a self-calibrating maximum-likelihood technique using momentum-weighted charge from the two hemispheres in each tagged event. From our 1994-1995 sample of 3.6 pb−1, having a luminosity-weighted average e− polarization of 77.3%, and our 1993 sample of 1.8 pb−1, having a luminosity-weighted polarization of 63.1%, we obtain A{sub b} = 0.848 " 0.046(stat.) " 0.050(syst.).

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Category :
Languages : en
Pages : 23

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We present an updated direct measurement of the parity-violating coupling of the Z° to strange quarks, A{sub s}, derived from the full SLD data sample of approximately 550,000 hadronic decays of Z° bosons produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1998. Z° → s{bar s} events are tagged by the presence in each event hemisphere of a high-momentum K{sup ±}, K{sub s} or [Lambda]°/{bar {Lambda}}° identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy-flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial s quark. The coupling A{sub s} is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. The background from u{bar u} and d{bar d} events is measured from the data, as is the analyzing power of the method for s{bar s} events. We measure: A{sub s} = 0.85 ± 0.06(stat.) {+-} 0.07(syst.)(preliminary).

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Category : Dissertation abstracts
Languages : en
Pages : 800

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Author: Thomas Robert Junk
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Category :
Languages : en
Pages : 528

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