以蒙地卡羅法研討Ｂ介子至質子Λ重子衰變

Monte Carlo Study of B+ → p(1520) Decay at Belle

林冠伯(Kuan-Po Lin)

指導教授 ： 王名儒

國立臺灣大學/理學院/物理學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201700568

摘要

本篇論文探討B介子經由B^+→pΛ ̅_1520→pp ̅K^+雙重子途徑之衰變。本實驗以蒙地卡羅法模擬日本高能加速器B介子工廠(KEKB)中Belle偵測器收集來自Υ(4S)共振態衰變的7億7千萬BB ̅介子對。本實驗並應用以神經網路演算法為基礎的NeuroBayes來提升訊噪比，以估計B^+→pΛ ̅_1520→pp ̅K^+分支比在90%信心水準下的上限值為5.46 × 10 −7 。此模擬結果可對Belle偵測器真實數據之分支比量測所幫助。相關主題亦值得於新一代B介子工廠(SuperKEKB)進行後續研究。

關鍵字

B介子 ； Belle ； KEKB

並列摘要

B+ → pΛ ̄1520 is one of the simplest two-body baryonic B decay modes. Wereconstruct Λ ̄1520 from ̄p and K+, then search for the signal B+ → pΛ1520(→ ppK ̄+). Simulating the data collected at the Υ(4S) resonance with the Belle detector at KEKB, we use Monte Carlo method to generate 772 million BB ̄ pairs collider events. After background suppression, we extract the signal from the Monte Carlo generated data and estimate the branching fraction:B(B+ → pΛ ̄1520) < 5.46 × 10−7 at the 90% confidence level. This study helps measuring the branching fraction of the real data at Belle detector, and further, data at Belle II detector.

並列關鍵字

B meson ； Belle ； KEKB ； NeuroBayes

參考文獻

[1] http://en.wikipedia.org/wiki/File:Standard Model of Elementary Particles.svg

[2] M.Kobayashi and T.Maskawa,”CP-Violation in the Renormalizable Theory of Weak Interaction”, Progress of Theoretical Physics 49, 2, 652-657 (1973)

[3] (Particle Data Group) http://pdg.lbl.gov/

[4] L.Wolfenstein, ”Parametrization of the Kobayashi-Maskawa Matrix”, Phys. Rev. Lett. 51, 1945-1947 (1983)

[5] S. W. Herb et al., ”Observation of a Dimuon Resonance at 9.5 GeV in 400-GeV Proton-Nucleus Collisions”, Phys. Rev. Lett. 39, 252-255 (1977)