大型强子对撞机上Bc介子产生、衰变和谱的研究

The heavy quarkonium physics is a hot topic in the theoretical physics. It play an important role in the test and development of standard model. And it is considered as the hydrogen atoms in the strong interaction. Bc meson is composed by different flavor heavy quarks. Then the Bc meson is generated mainly through the strong interaction but decayed through the weak interaction. So the Bc meson is an excellent lab to the understand the perturbative and non-perturbative quantum chromodynamics, electroweak interaction. The Bc meson production cross sections in Tevatron is much large than theoretical prediction. At the same time, a lot of new charmonium and bottomonium states is observed. There are many hot and important topic in heavy quarkonium physics, especial Bc. This project focus on Bc meson production in hadron colliders, the Bc family meson spectroscopy, as well as the Bc meson decay. Several similar related issues will be studied too, such as the heavy quarkonium production associated with heavy quarks. The project plans to study the urgent problem of heavy quarkonium physics. Study the production, decay and spectroscopy of Bc through the application of automatic calculation of computer algebra. This study is meaningful in understanding of the heavy quark interactions between the perturbative and non-perturbative quantum chromodynamics (QCD), test the standard model and probing new physics model. The project team has accumulated in the relevant direction a lot of experience to ensure the project is successfully completed.

重夸克偶素在准模型中具有重要意义，被誉为是强相互作用中的"氢原子"。Bc介子是由不同味道的重夸克组成的束缚态，因此Bc介子主要是强相互作用产生而弱相互作用衰变，从而它的产生、衰变和谱的研究在理解微扰与非微扰QCD、电弱相互作用等方面具有特殊的地位。Tevatron上Bc的产生截面远大于理论预言，且近期实验家发现很多新的粲偶素、底偶素。对于重夸克偶素,特别是Bc介子还有很多迫切需要研究的问题。本课题主要研究内容有Bc介子在强子对撞机上的产生，Bc族介子的能谱，以及Bc介子的衰变，同时也将研究类似课题，比如重夸克偶素伴随重夸克的产生等。本项目针对重夸克偶素物理中迫切需要解决的问题申请立项，通过计算机自动计算来研究Bc的产生、衰变和谱，计划探索的课题对于理解重夸克间的相互作用、检验标准模型和探测新物理模型具有重要意义。同时本项目组在相关方向已经积累了大量的经验，能保证本项目顺利。

本项目针对重夸克偶素物理中迫切需要解决的问题申请立项，通过计算机自动计算来研究相关问题。在项目执行期间，密切关注学科动态，在重夸克偶素产生方面开展研究。在本项目的支持下，完成了强子对撞机上 J/ψ 和 Υ 联合产生、正负电子对撞中 J/ψ 色八重态矩阵元的研究、B_{s,d}^* 的轻子对衰变及其对B_{s,d} 的轻子对衰变的影响、正负电子对撞中C=+的粲偶素伴随光子产生的alpha_s v^2 阶修正、BESIII上伴随光子产生的C=+粲偶素和XYZ粒子、干涉效应对CEPC上Higgs质量通过双光子道测量的影响等工作。重要结果包括发现强子对撞机上 J/ψ 和 Υ 联合产生应该是双部分子占90%以上，因此此过程是一个优秀的研究双部分子散射的探针；发现强子对撞机和正负电子对撞机对 J/ψ 色八重态矩阵元要求不一致，因此相关问题还需要更深入的研究；发现B_{s,d}^* 会改变B_{s,d}达到3%左右。在本项目支持下，已经以通讯作者发表包含PRL在内的SCI论文7篇，EI 论文1篇。