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(Unpublished)
Abstract
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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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| 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 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45604 |
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