A study of the tau Lepton polarization in Z0 decays

Altoon, Butrus Youkhana (1991) A study of the tau Lepton polarization in Z0 decays. PhD thesis, University of Glasgow.

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Abstract

A study is presented of tau polarization observed in the channel Z° → tau+tau- and the subsequent tau decay tau →pinutau, using the ALEPH detector at the LEP collider at CERN. The polarization is a result of parity violation in the neutral and charged weak interactions. Experimentally it can be measured from the energy spectrum of the tau decay product. The detector started collecting data in 1989 and the data were taken in a range of energy in the vicinity of the Z0 pole. Observation of a non-zero polarization confirms that parity is violated in weak interactions, extending its proven existence in neutral weak currents to tau lepton interactions in agreement with the universality of the electroweak theory. Tau polarization is directly related to the ratio of the vector and axial vector couplings of the tau lepton to Z0 and hence to the effective electroweak angle Using the partial width of the Z0 decays to the tau lepton measured by this experiment, the tau couplings to the Z0 were found to be atau = -0.4969+/-0.0173 and vr = -0.035+/-0.0119.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: High energy physics.
Subjects: Q Science > QC Physics
Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
Supervisor's Name: Smith, Prof. Ken
Date of Award: 1991
Depositing User: Enlighten Team
Unique ID: glathesis:1991-78335
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 28 Feb 2020 12:09
Last Modified: 26 Mar 2020 11:54
URI: http://theses.gla.ac.uk/id/eprint/78335

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