Real-time alignment of the LHCb vertex detector and observation of charmless baryonic decays B(s) --> p anti-p h+ h'-

  • Giulio Dujany

Student thesis: Phd


This thesis presents measurements of the branching fractions of the charmless baryonic decays B(s) --> p anti-p h+ h'-, where h(') denotes a kaon or a pion. Three new modes (B --> p anti-p pi+ pi-, Bs --> p anti-p K+ K- and Bs --> p anti-p K+(-) pi-(+)) are observed for the first time and evidence is found for a fourth (B --> p anti-p K+ K-). The inclusive branching fraction of B --> p anti-p K+(-) pi-(+) is measured for the first time and the upper limit is set on the branching fraction of the Bs --> p anti-p pi+ pi- decay. This represents the first observation of four-body charmless baryonic decays of a Bs meson and one of the first observations of baryonic Bs decays. The implementation of the real-time alignment of LHCb's vertex detector is also described. The novel real-time alignment and calibration strategy adopted by LHCb is essential to allow more stable data taking conditions and an optimal ``offline-quality'' reconstruction to be performed at the trigger level, ensuring more efficient trigger selections and the possibility to perform physics analyses directly on the trigger output.
Date of Award1 Aug 2017
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorChristopher Parkes (Supervisor) & George Lafferty (Supervisor)


  • Alignment
  • Real-time
  • LHCb
  • Branching fraction
  • Bs decays
  • B decays
  • Charmless
  • Baryonic
  • Flavour physics

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