对重味物理领域超标准模型新物理效应的实验探索和理论研究

Study of heavy flavour physics plays a key role for search of new physics and understanding its property, due to its ability to explore physics far above the TeV scale and provide key information about its couplings. However，full exploitation of its potential is currently limited by insufficent measurement precision and sizeable uncertainties in prediction of some quantities. The applicants used LHCb data to study CP violation and rare decays of the B system, and achieved some important physics results, including the most precise measurement of Bs mixing phase. Based on these studies, they propose a comprehensive research plan: 1) expoit the big amount of LHCb data to be collected in the next few years to significantly improve measurement precision and expand the scope of search for new physics; 2) develop new theoretical calcualtion tools in order to benefit Standard Model predictions; 3)pursue phenomenological study in order to identify new observables that are sensitive ot new physics, and investigate implications of new experimental results; 4) prepare for physics analysis with data from upgraded LHCb detector. These efforts will largely improve our ability to probe new physics effects in the heavy flavour sector, help us to enrich our knowledge of the energy scale and flavour structure of new physics, and fully understand the origin of CP violation..

重味物理研究能够探测能量远高于1TeV的新物理，提供关于新物理耦合常数的关键信息，对寻找新物理和了解其特性具有关键作用。但其潜力的充分发挥目前受限于测量精度不足和标准模型预言不确定性较大这两个因素。申请人和项目组成员近年来基于LHCb数据对B介子的CP破坏和稀有衰变开展了研究并取得了包括Bs混合角的最精确测量在内的一系列重要成果。在此基础上，提出了一个系统性研究计划来进一步探索新物理：１）利用LHCb未来几年大幅增加的数据量开展对B和D介子的CP破坏和稀有衰变的研究，进一步提高测量精度和扩大搜索范围；２）发展理论计算方法，提高标准模型预言的精度；３）开展唯象研究，开发对新物理敏感的新观测量和探讨测量结果对新物理的意义；4）为LHCb升级后的进一步探索做准备。这些研究将较大地提高我们在重味领域探索新物理的能力，有助于加深我们对新物理能区和味道结构的认识，和深刻理解CP破坏的来源。

重味物理是高能物理的前沿领域。在实验方面，我们利用LHCb探测器于2011-2018年采集的质子质子对撞数据研究重味强子的性质。重点开展了Bs介子系统的CP破坏研究，取得了Bs介子混合角phi_s的世界最精确测量结果，能对新物理模型的构建作出重要限制。开展了若干b->s非轻衰变的研究，测量了Bs->phi phi过程的CP破坏，设置了稀有衰变B0->phi phi的分支比上限，首次观察到Bs->phi pi+ pi-衰变。在强子谱学领域，我们首次发现了五夸克态和双粲重子，并对它们的性质进行了深入研究。在理论方面，开展了若干重味物理前沿问题的研究，包括b强子衰变两圈QCD修正的计算，R(D(*))异常结果的新物理唯像解释和模型无关分析等。这些研究成果对探索新物理效应、理解强相互作用动力学机制具有重要意义。基于研究工作发表论文56篇，作国际会议报告40余次。