Development of a tracker for LHCb and the study of rare charm decays

  • Zakariya Aliouche

Student thesis: Phd

Abstract

A search for rare charm decays of the form D ->hll is conducted, where h is a charged pion or kaon, and l is an electron or muon. The analysis is performed with a common methodology across 25 decay channels of this form. This includes channels which, outside resonance contributions, are highly suppressed in the Standard Model and channels which are forbidden in the Standard Model by Lepton Flavour Violation. This analysis is potentially sensitive to beyond the standard model processes. It is performed on a data sample collected by the LHCb experiment in 2017 and 2018, corresponding to 1.7 fb$^{-1}$ and 2.1 fb$^{-1}$ of integrated luminosity respectively. It is anticipated that world-best limits will result from this analysis, though the datasets are currently blinded, as the analysis has not yet undergone LHCb's internal review procedure. This thesis also reports studies for the Upgrade II of the LHCb experiment, which is planned to be installed in the 2030s. The studies in this thesis concern the design of a new tracking system, including CMOS pixel sensors in the inner region of the main tracker, known as the Mighty Tracker. Tracking studies are presented that have been used in the design of this tracker. A track matching algorithm is used to study the required detector resolution. These demonstrate the importance for high luminosity operation of having this pixel region to provide good resolution in the non-bending plane as well as in the bending-plane of the tracks. This study provides the first demonstration that such a system may achieve the required tracking performance for the experiment in the Upgrade II environment. A characterisation of an early CMOS sensor prototype for the LHCb Mighty Tracker, the MightyPix (run2020v5), is conducted. A test setup has been commissioned and threshold scans across the pixel matrix of the sensor performed. This allowed for performance parameters to be extracted, and compared across the pixel matrix, comparing the results from eight different flavours of pixel on the prototype. These studies are useful in cataloguing the performance of these flavours for use in future design iterations.
Date of Award1 Aug 2024
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorChristopher Parkes (Supervisor) & Marco Gersabeck (Supervisor)

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