Branching ratios of charmed baryons in the LHCb experiment

Ogilvy, Stephen (2015) Branching ratios of charmed baryons in the LHCb experiment. PhD thesis, University of Glasgow.

Abstract

LHCb is the dedicated heavy flavour experiment on the LHC accelerator ring. An analysis measuring the relative branching fractions of Lc->phh decays is presented using 1 inverse femtobarn of proton - proton collisions gathered by LHCb during 2011.
Independent measurements are made using samples of Lc produced from the primary interaction and from those produced in semileptonic decays of Lb baryons.
The measured relative branching ratios in the prompt analysis are
B(Lc->pK-K+)/B(Lc->pK-pi+) = (2.03 ± 0.07 (stat) ± 0.10 (syst)) × 10−2, and
B(Lc->ppi-pi+)/B(Lc->pK-pi+) = (7.04±0.19(stat)±0.34(syst))×10−2,
while in the semileptonic analysis they are measured to be
B(Lc->pK-K+)/B(Lc->pK-pi+) = (1.68 ± 0.03 (stat) ± 0.04 (syst)) × 10−2, and
B(Lc->ppi-pi+)/B(Lc->pK-pi+) = (7.45±0.06(stat)±0.24(syst))×10−2.

In the semileptonic analysis we make the first observation of the decay mode Lc->pK+pi- with a significance of 11.1 sigma. We measure the ratio:
B(Lc->pK+pi-)/B(Lc->pK-pi+) = (1.62±0.15(stat)±0.05(syst))×10−3.

Charged hadron discrimination in LHCb is provided by two ring imaging Cherenkov detectors. A data-driven study on the performance of the aerogel Cherenkov radiator is presented. Particle identification information is used to construct variables describing the likelihood of hadronic particle hypotheses of reconstructed tracks, on which cuts are placed in typical physics analyses. The preparation of new data samples allowing for the data-driven efficiency correction of particle identification cuts on proton tracks is described.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: particle physics, charmed baryons, LHCb, RICH, Lc->phh
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Soler, Prof. Paul
• Date of Award: 2015
• Depositing User: Mr Stephen Ogilvy
• Unique ID: glathesis:2015-6463
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 Jun 2015 08:28
• Last Modified: 16 Jun 2015 14:21
• URI: https://theses.gla.ac.uk/id/eprint/6463