“核科学与技术”青年论坛—— 杨友华博士
应兰州大学核科学与技术学院、稀有同位素前沿科学中心邀请，法国巴黎综合理工学院LLR实验室博士后研究员杨友华博士将于2025年8月9日来校进行学术交流并作报告。
报告题目：Amplitude analysis of B+→K+π+π- decays in LHCb
报告时间：2024年8月9日（星期六）10：00
报告地点：兰州大学理工楼1126室
腾讯会议： 432-6392-6819
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【报告摘要】
Abstract: This report presents a comprehensive analysis of the charmless three-body decay B+→K+π+π-, leveraging a dataset corresponding to 3fb-1 of pp collisions at s=7 and 8 TeV recorded by the LHCb detector. The study focuses on branching fractions and CP-violating asymmetries of intermediate resonances, employing three complementary amplitude-modeling approaches: an analytic isobar model, the K-matrix formalism, and a quasi-model-independent partial-wave analysis. Notably, the isobar model, enhanced by advanced dispersive π+π- scattering amplitudes, achieves superior fit quality over the K-matrix for the first time in comparable analyses.
Significant CP-violation effects are observed, including short-distance CP violation in B+→ρ(770)0K+ decays and long-distance effects in B+→f2(1270)K+ decays. First evidence for CP violation involving spin-3 resonances and ππ rescattering is reported, alongside interference phenomena between partial waves (S-P and S-D). The analysis also resolves longstanding ambiguities in the Kπ S-wave component, demonstrating that decoupling the K0*(1430)0resonance from non-resonant contributions aligns B+→K0*(1430)0π+ branching fractions with QCD factorisation predictions. Additionally, ten new intermediate decays are identified, and the K0*(1950)0 resonance is supported. These results provide critical constraints on penguin amplitudes and advance understanding of strong dynamics and CP-violation origins in B+→K+π+π- decays.
【报告人简介】
杨友华博士现为法国巴黎综合理工学院LLR实验室博士后研究员。2019年获南京大学博士学位，2019–2023年于中国科学院大学、2023–2025年于意大利热那亚大学从事博士后研究。他2015年加入BESIII实验，2019年加入LHCb实验，并于2020–2024年担任LHCb实验"BnoC"物理工作组分波分析小组召集人，专注于高能物理实验数据分析并参与LHCb实验RICH探测器升级工作。
研究方向涵盖重味物理多个前沿领域：通过Ds？半轻衰变（形状因子测量）和纯轻衰变（衰变常数与CKM矩阵元提取）精确检验标准模型。多体B衰变的振幅分析、CP破坏与QCD动力学检验。
核科学与技术学院
稀有同位素前沿科学中心
2024年8月7日
