Thesis BELLE2-MTHESIS-2023-026

The study of B0 to J/ψ eta in Belle II Experiment at KEK

Yuan-Hao Hsu

Fu Jen Catholic University New Taipei, Taiwan

Abstract: We study the decay of 𝐡0 β†’ π½β„πœ“ eta based on the Belle data samples at the Ξ₯(4𝑆) resonance and compare to the results in PRL 2007 β€œObservation of the Decay 𝐡0 β†’ π½β„πœ“ eta ” and PRD 2012 β€œMeasurement of 𝐡0 β†’ π½β„πœ“ eta(β€²) and constraint on the eta βˆ’ etaβ€² mixing angle”. The branching fraction is (9.5 Β± 1.7 Β± 0.8) Γ— 10^βˆ’6, and the significance is 8.1 𝜎 in PRL 2007. The branching fraction is (12.3 + 1.8 -1.7 Β± 0.7) Γ— 10^βˆ’6, and the significance is 6.3𝜎 in PRD 2012. In this study, we use the Monte Carlo method to generate the expected rare decay 𝐡0 β†’ π½β„πœ“ eta in the Belle II experiment environment for physical event simulation and use the Belle II software analysis module (basf2). The B mesons are generated by the electron-position collider (KEKB) in the High Energy Accelerator Research Organization (KEK) and collected by Belle Detector. The total number of BB-bar events is 771 million. We convert the Belle mdst to Belle II mdst by the module B2BII. The branching fraction of 𝐡0 β†’ π½β„πœ“ eta in our study is (10.9 Β± 1.6 Β±1.2)Γ— 10^βˆ’6. The significance is 8.7𝜎. The difference between this analysis method and the previous two published results is that this study uses the Belle II detector simulation instead of Belle's. The optimized selections of variables are also based on the environment of the Belle II detector. The significance of the branching fraction in this study is increased a bit, but the errors are also increased a bit.

Note: Presented on 20 01 2021
Note: MSc

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 Record created 2023-05-28, last modified 2023-05-29

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