Theoretical Physics

这项提议中的PI将在理论物理中的各种令人兴奋的领域进行研究，包括标准模型的扩展、电弱对称破缺、量子色动力学、中微子物理、超对称性、量子场论中的反常和边界条件、保形场论、超弦的量子化和弦紧致的几何。量子场论是基本粒子和力的语言。在量子场论中，所谓的标准模型描述了自然界中除引力之外的已知作用力，即电磁力、弱力和强力。标准模型没有解决的谜团之一是“世代”问题，即粒子类型的三倍重复。另一个问题是电弱对称破缺的起源，也就是弱相互作用是如何变弱的。人们普遍希望，欧洲核子研究中心的大型强子对撞机将在未来几年内开始对这些问题提供质的新见解。事实上，预计许多关于扩展标准模型的建议，特别是那些具有超对称性的建议，将受到考验。在超对称模型中，所有已知的粒子都有尚未被检测到的“伙伴”，他们的存在改善了理论的量子行为。近年来的实验也证实，中微子只通过弱作用力相互作用，质量很小，但质量不为零，这在标准模型的构建中是没有预见到的。中微子的质量对天体物理学和宇宙学也有深远的影响。标准模型中的强力由场论量子色动力学(QCD)描述，这是观察新信号的实验计划的核心。它还展示了量子场论中尚未被理解的关键方面，并呈现出“弱耦合”和“强耦合”两种行为。在弱耦合或微扰中工作，QCD既可以对新物理的信号及其背景进行预测。研究了该理论的强耦合行为，以了解核子结构以及它与包括弦理论在内的其他理论的关系。弦理论是唯一已知的引力有限量子理论，它激发了对量子场理论的许多新的见解，特别是QCD及其超对称扩展。它是一个统一了所有已知力量的理论的唯一候选者。它让人们对黑洞的本质有了深刻的了解，并揭示了与现代数学的许多方面的深刻联系。它为在大型强子对撞机上看到新物理学提出了许多建议。这项拟议的研究将产生广泛的影响，促进我们对自然规律的了解，并有助于更好地理解物理宇宙。事实上，资深参与者正在研究的许多话题都在媒体上得到了广泛的讨论，例如，中微子在宇宙中的作用，以及物理学家对即将投入使用的大型强子对撞机的希望。这项建议中概述的研究将服务于研究生和博士后研究员的培训。这项提案的教职员工经常参与推广工作，以接触到更广泛的公众。其中包括通过邵逸夫系列的公开讲座，以及西蒙斯基金会资助的物理和数学夏季研讨会。他们还参与为研究生编写教科书。

The PIs on this proposal will perform research in a variety of exciting areas in theoretical physics, including extensions of the Standard Model, electroweak symmetry breaking, quantum chromodynamics, neutrino physics, supersymmetry, anomalies and boundary conditions in quantum field theory, conformal field theory, the quantization of the superstring, and the geometry of string compactifications. Quantum field theory is the language of elementary particles and forces. Among quantum field theories, the so-called Standard Model describes the known forces in Nature aside from gravity, namely the electromagnetic, weak and strong forces. Among the mysteries not addressed by the Standard Model is the problem of "generations", a three-fold repetition of particle types. Another is the origin of electroweak symmetry breaking, or precisely how the weak interactions become weak. It is widely hoped that the Large Hadron Collider at CERN will begin providing qualitatively new insights into these issues within the next few years. Indeed, it is expected that many proposals for extensions of the Standard Model, especially those with supersymmetry, will be tested. In supersymmetric models, known particles all have as-yet undetected "partners", whose presence improves the quantum behavior of the theory. Experiments over recent years have also confirmed that neutrinos, which only interact via the weak forces, have small but nonzero masses, not envisioned in the construction of the Standard Model. Neutrinos masses also have profound consequences for astrophysics and cosmology. The strong force in the Standard Model is described by the field theory quantum chromodynamics (QCD), which is central to experimental programs for observing new signals. It also exhibits crucial aspects of quantum field theory that are not yet understood, and presents both "weak coupling" and "strong coupling" behaviors. Work in weak-coupling, or perturbative, QCD serves both to make predictions for signals of new physics and their backgrounds. The strong-coupling behavior of the theory is studied to understand the structure of the nucleons, and for its relation to other theories, including string theory. String theory is the only known finite quantum theory of gravity, and has inspired many new insights into quantum field theories, especially QCD and its supersymmetric extensions. It is the only candidate for a theory that unifies all the known forces. It has given insights into the nature of black holes and revealed profound links to many aspects of modern mathematics. It suggests many proposals for new physics to be seen at the LHC. The proposed research will have a broad impact by advancing our knowledge of the laws on Nature and contributing toward a better understanding of the physical universe. Indeed, many of the topics under study by the senior participants are widely discussed in the media, such as the role of "ghostly" neutrinos in the Universe, and hopes of physicists for the soon-to-be-commissioned Large Hadron Collider. The research outlined in this proposal will serve in the training of graduate students and postdoctoral fellows. The faculty on this proposal are often involved in outreach efforts to reach a broader public. These include public lectures through the Run Run Shaw series and summer workshops in physics and mathematics supported by the Simons foundation. They are also involved in writing textbooks for graduate students.