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Charged kaon and proton production in B-hadron decays
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics.
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The production of charged kaons and protons in B-hadron decays has been measured in e+e- annihilations at centre-of-mass energies corresponding to the Z0 mass. In total 1.6 million hadronic Z0 decays were analysed, corresponding to about 690000 B-hadron decays. They were collected using the DELPHI detector at the LEP collider at CERN during 1994 and 1995.

Events containing B-hadron decays were identified using special characteristics of the B-hadron decay topology. In particular, the long lifetime of the B-hadron leads to decay vertices significantly displaced relative the interaction point. These so called secondary vertices were reconstructed using a powerful micro vertex detector. In order to discriminate B-hadron decay products from fragmentation tracks, a method was used where the impact parameter measured by the vertex detector was employed as a discriminating variable. The tracks were thus divided into two classes, one compatible with the interaction point and the other compatible with a secondary vertex. An unfolding method was used to extract the true B-hadron decay tracks from the two classes. Charged kaons and protons were identified using the Ring Imaging CHerenkov (RICH) detector and corrected for misidentification using an efficiency matrix. The analysis resulted in charged kaon and proton spectra from B-hadron decays, including previously unmeasured momentum regions. Integrating the spectra yielded the following multiplicities

n(B-hadronK±X) = 0.683±0.021(stat) ±0.017(syst)

n(B-hadronp/ p¯X) = 0.127±0.013(stat) ±0.019(syst)

where the proton multiplicity does not include Λ baryon decay products.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2001. , 135 p.
Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-2516 ; 27
Keyword [en]
Radiation sciences, Högenergifysik, LEP, DELPHI, B-hadron, proton, kaon
Keyword [sv]
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
High Energy Physics
URN: urn:nbn:se:uu:diva-1260ISBN: 91-554-4900-XOAI: oai:DiVA.org:uu-1260DiVA: diva2:160822
Public defence
2001-03-02, Häggsalen (sal 10132), Ångströmlab, Uppsala, 10:15
Available from: 2001-02-09 Created: 2001-02-09 Last updated: 2010-10-15Bibliographically approved

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