Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301953
Title: Measurements of the mass of the W boson in the W⁺W⁻ → qq̄qq̄ channel with the ALEPH detector
Author: Chalmers, Matthew Donald Kennedy
ISNI:       0000 0001 3526 1639
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1999
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Abstract:
A measurement of the mass of the W boson from e+e- → W+W- → qq¯qq¯ events is presented, from LEP data collected at √s= 189 GeV during 1998 with the ALEPH detector. The procedure of direct reconstruction of the W+W- final state invariant mass distribution is adopted, with an optimisation of the event selection and jet clustering algorithms. A two dimensional Monte Carlo reweighting technique is used to extract the W mass and a full discussion of the systematic uncertainties is given. The W mass is measured to be: MW = 80.556 +/- 0.110(stat.) +/- 0.039(syst.) +/- 0.056(F.S.I.) +/- 0.017(LEP) GeV/c2. A new technique for extracting the W mass using a two dimensional Kolmogorov Smirnov test is introduced. The W mass using this method is measured to be: MKSW = 80.423 +/- 0.160(expected stat.) GeV/c2, which is compared with that from the method of maximum likelihood. Rigorous optimisation and stability checks on the W mass estimator and its error are presented, and the result put into the context of a LEP and subsequently world average value: MworldW = 80.394 +/- 0.042 GeV/c2. The implications of this result are interpreted by comparing it with the indirect W mass measurement from the Standard Model prediction: MindirectW = 80.381 +/- 0.026 GeV/c2. A discussion and outlook for the W mass measurement at LEP is given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.301953  DOI: Not available
Keywords: W PLUS BOSONS; W MINUS BOSONS; MASS; QUARKS; GEV RANGE 100-1000; MONTE CARLO METHOD; EXPERIMENTAL DATA
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