Measurement of Λ polarization from Z decays

Buskulic, D. and Finch, Alexander (1996) Measurement of Λ polarization from Z decays. Physics Letters B, 374 (4). pp. 319-330. ISSN 0370-2693

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The polarization of Λ baryons from Z decays is studied with the Aleph apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Λ polarization is PLΛ = −0.32 ± 0.07 for . This agrees with the prediction of −0.39 ± 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for Λ production. The observed Λ polarization is diluted with respect to the primary s quark polarization by Λ baryons without a primary s quark. Measurements of the Λ forward-backward asymmetry and of the correlation between back-to-back Λ pairs are used to check this dilution. In addition the transverse Λ polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the Λ direction.

Item Type: Journal Article
Journal or Publication Title: Physics Letters B
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/3100/3106
Departments: Faculty of Science and Technology > Physics
ID Code: 64056
Deposited By: ep_importer_pure
Deposited On: 09 May 2013 15:48
Refereed?: Yes
Published?: Published
Last Modified: 03 Dec 2019 03:33

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