Strong interaction effects in exclusive B decays

独家 B 衰变中的强相互作用效应

• 批准号: SAPGP-2014-00002
• 负责人: Ahmady, Mohammad
• 金额: $ 1.82万
• 依托单位: Mount Allison University
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Group
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567999
• 关键词: Strong; interaction; effects; exclusive; decays

With the Large Hadron Collider (LHC) first run successfully completed in 2013 and a wealth of data being continuously analysed and published, the physics of the B mesons, i.e. mesons containing a b quark, has entered a new exciting era. One of the four main experiments at the LHC, namely the LHCb experiment, is dedicated to the study of the B mesons. Their numerous decay channels offer the opportunity to make precision tests of the Standard Model (SM) and perhaps more interestingly, to discover new physics beyond the SM. Data taking will resume in 2015 at peak energy and higher luminosity. In the next 5 years, various observables will be measured with increasing precision by the LHCb collaboration and theory input will clearly be required to interpret the data as well as to guide future experiments in this field. In this research, we focus on rare exclusive B decays to light mesons, i.e. B decays to specific final products. Such decays are especially appealing because they are relatively easy to access experimentally especially in an environment like the LHC. On the other hand, the theory of such decays is challenging because they involve strong interactions effects which are not computable using perturbation theory in Quantum Chromodynamics (QCD), the fundamental modern theory of strong interactions. In our research, we model these effects by using a relatively new technique which involves exploiting a correspondence between QCD in physical spacetime and a string theory in a higher dimensional curved space called anti de Sitter (AdS) space. This correspondence is called AdS/QCD. At the same time, we will investigate signals of new physics in those rare B decays. These rare decays are sometimes quite susceptible to the interference from much heavier particles that may be out there but have not been discovered yet. Our proposed investigation is to have a better understanding of these interferences which can then be compared with the experimental data from the LHC. This comparison will hopefully give us some clues on how the SM can be extended towards a more complete theory. With our research, we hope to contribute to the efforts of the particle physics community to discover new physics at the LHC. At the same time, we are testing AdS/QCD which offers insights into the unsolved problem of confinement of quarks in hadrons.

随着2013年大型强子对撞机（LHC）首次运行成功，大量数据不断被分析和发表，B介子（即含有B夸克的介子）物理学进入了一个令人兴奋的新时代。LHC的四个主要实验之一，即LHC B实验，致力于研究B介子。它们众多的衰变通道提供了对标准模型（SM）进行精确测试的机会，也许更有趣的是，可以发现SM之外的新物理。数据采集将在2015年以峰值能量和更高亮度恢复。在接下来的5年里，LHCb合作将以越来越高的精度测量各种可观测量，显然需要理论输入来解释数据并指导该领域的未来实验。在本研究中，我们主要关注稀有的B衰变到轻介子，即B衰变到特定的最终产物。这种衰变特别吸引人，因为它们相对容易在实验上获得，特别是在LHC这样的环境中。另一方面，这种衰变的理论是具有挑战性的，因为它们涉及到强相互作用效应，而这些效应是不能用量子色动力学（QCD）中的微扰理论计算的，量子色动力学是强相互作用的基本现代理论。在我们的研究中，我们通过使用一种相对较新的技术来模拟这些效应，该技术涉及利用物理时空中的QCD与称为反德西特（AdS）空间的高维弯曲空间中的弦理论之间的对应关系。这种对应称为AdS/QCD。同时，我们也将研究这些罕见的B衰变中的新物理信号。这些罕见的衰变有时很容易受到可能存在但尚未被发现的重得多的粒子的干扰。我们建议的调查是有一个更好的了解这些干扰，然后可以与LHC的实验数据进行比较。这种比较将有望给我们一些线索，如何SM可以扩展到一个更完整的理论。通过我们的研究，我们希望为粒子物理学界在LHC发现新物理的努力做出贡献。与此同时，我们正在测试AdS/QCD，它提供了对强子中夸克禁闭的未解决问题的见解。