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Search for Baryon-Number-Violating Processes in $B^-$ Decay to Final State $\overline{\Xi}_c^0 \overline{\Lambda}_c^-$ at Belle and Design of Belle II TOP Trigger System

Gu, Tianping (2024) Search for Baryon-Number-Violating Processes in $B^-$ Decay to Final State $\overline{\Xi}_c^0 \overline{\Lambda}_c^-$ at Belle and Design of Belle II TOP Trigger System. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This dissertation has two parts which describe my work on the Belle and Belle~II experiments. The first part provides a detailed account of my search for baryon-number violating processes using Belle data. The second part outlines my contributions to the Belle~II trigger based on information from Time-of-Propagation (TOP) counters.

In the first part I report the results of the first search for $B^-$ decay to final state $\overline{\Xi}_{c}^{0} \overline{\Lambda}_{c}^{-}$ using 711~${\rm fb^{-1}}$ of data collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The results are interpreted in terms of a direct baryon-number-violating $B^-$ decay and, alternatively, in terms of $\Xi_{c}^{0}-\overline{\Xi}_{c}^{0}$ oscillations which follow the Standard Model decay $B^- \to \Xi_{c}^{0} \overline{\Lambda}_{c}^{-}$. No evidence for baryon number violation is observed and 95\% confidence-level upper limits are set on the ratio of baryon-number-violating and Standard Model branching fractions ${\mathcal{B}(B^- \rightarrow \overline{\Xi}_{c}^{0} \overline{\Lambda}_{c}^{-})}/{\mathcal{B}(B^- \rightarrow \Xi_{c}^{0} \overline{\Lambda}_{c}^{-})} < 2.7\%$ and on $\Xi_{c}^{0} - \overline{\Xi}_{c}^{0}$ oscillation angular frequency $\omega < 0.76\ \mathrm{ps}^{-1}$.

In the second part I report on my studies in the area of TOP-based trigger system (TOP~TRG) which provides precise collision timing information for the Belle~II Trigger system. The development of TOP~TRG system, including the hardware, firmware design, and performance analysis are presented. The standalone TOP~TRG achieves the efficiency of 92.5\% for barrel cosmic muons. By incorporating CDC-TOP matching, an efficiency of 75\% and a timing resolution of 12~ns are achieved for hadronic events. I discuss further possible TOP~TRG improvements.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Gu, Tianpingtig20@pitt.edutig200000-0002-1470-6536
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSavinov,
Committee MemberAlison,
Committee MemberBatell,
Committee MemberSalman,
Committee MemberMueller,
Date: 10 January 2024
Date Type: Publication
Defense Date: 5 December 2023
Approval Date: 10 January 2024
Submission Date: 6 December 2023
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 257
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Particle Physics, Detector Firmware
Date Deposited: 10 Jan 2024 14:31
Last Modified: 10 Jan 2024 14:31


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