以蒙地卡羅法研討Ｂ介子至質子Λ重子衰變

Abstract

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。

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.