Theoretical Studies of Particles and Strings

我们的最终目标是理解物质和力的本质，以及整个宇宙的内容和演化。物理学家尤金·维格纳（Eugene Wigner）所说的“数学在自然科学中不可思议的有效性”是现实中最有趣的特征之一，它能够对观察到的现象提供准确和预测性的描述。作为理论物理学家，我们通过激发和构建物理系统的数学模型来利用这一点，为此我们还尽可能设计实验测试，因为这些最终是真理的仲裁者。我们的重点是物质的基本成分和相互作用，既在标准模型（SM）的强，弱和电磁相互作用中，也在寻找不能被SM解释的现象的理解，比如量子引力。实验上，有许多方法试图理解这些基本成分和相互作用。基本粒子可以在欧洲核子研究中心（CERN）的大型强子对撞机（LHC）等加速器上产生和研究。我们也可以通过极端天体物理环境中产生的宇宙射线，以及宇宙早期遗留下来的宇宙学和引力波特征来了解它们。我们的理论工作以多种方式陪伴和补充这些实验工作：我们确定了基本粒子和相互作用的具体理论的实验和观测结果，这些理论试图解释一些主要的未解之谜，如暗物质的性质。我们考虑了广泛的潜在特征，包括引力波，高能宇宙射线，大型强子对撞机等对撞机中的现象以及基于新量子技术的一系列高灵敏度实验中的表现。我们还研究已知的现象，如黑洞的产生，在多大程度上可以解释诸如暗物质之类的谜团。我们探索弦理论，它提供了理解如何调和量子力学和引力的可能性。这提供了一个极其丰富的理论框架，提供了许多研究途径。例如，弦理论自然包含了比我们所熟悉的四个时空维度更多的维度，我们试图理解这些维度是如何折叠起来的，从而使我们无法察觉。我们探索量子引力理论的内部一致性条件，并在弦理论中设计计算技术。机器学习被用来帮助我们在弦理论提供的大量时空几何中导航。已知的和提出的基本相互作用的新理论通常都涉及到底层粒子强烈相互作用的状态。例如，对于已经确立的强作用力理论——量子色动力学来说，情况就是如此。在强相互作用的制度中，将潜在理论的特征与潜在的实验观察联系起来是具有挑战性的，我们的部分努力致力于设计方法，以更好地理解强相互作用理论的后果，无论是在弦理论中，它提供了许多研究强相互作用的框架，还是在现象学应用的角度。我们也付出了相当大的努力来预测弱相互作用的理论。为了从欧洲核子研究中心（CERN）大型强子对撞机（LHC）研究的希格斯玻色子和其他粒子的高精度数据中得出结论，这一点尤为重要。如何对弱相互作用理论进行预测的基本原理已经建立，然而将它们付诸实践带来了巨大的挑战，我们试图通过新颖的数学，计算和物理方法来解决这些挑战。

Our ultimate aim is to understand the nature of matter & forces, and the content & evolution of the universe as a whole. One of the most intriguing features of reality is what the physicist Eugene Wigner called "the unreasonable effectiveness of mathematics in the natural sciences" in being able to provide an accurate & predictive description of observed phenomena. As theoretical physicists we exploit this by motivating and constructing mathematical models of physical systems, for which we also devise experimental tests whenever possible, as these are ultimately the arbiter of truth.Our focus is on the fundamental constituents and interactions of matter, both within the Standard Model (SM) of the strong, weak & electromagnetic interactions, and searching for understanding of phenomena not explained by the SM, such as quantum gravity.Experimentally, there are many ways of attempting to understand these fundamental constituents and interactions. Fundamental particles can be produced and studied at accelerators like the Large Hadron Collider (LHC) at CERN. It is also possible to learn about them from the cosmic rays produced in extreme astrophysical environments and through cosmological and gravitational wave signatures left over from the early stages of the universe.Our theoretical work accompanies and complements such experimental work in multiple ways:1. We determine the experimental and observational consequences of concrete theories of fundamental particles & interactions that attempt to explain some of the major open mysteries such as the nature of dark matter. We consider a broad range of potential signatures, including gravitational waves, high-energy cosmic rays, phenomena at colliders such as the LHC and manifestations in a range of highly sensitive experiments based on new quantum technologies. We also examine to what extent known phenomena, such as black-hole production, could explain mysteries such as dark matter.2. We explore string theory, which offers the possibility of understanding how to reconcile quantum mechanics and gravity. This provides an extremely rich theoretical framework, offering many avenues to study. For example, string theory naturally involves many more dimensions than four spacetime dimensions that we are familiar with and we attempt to understand how those dimensions can be folded up so as to be imperceptible to us. We explore internal consistency conditions on theories of quantum gravity, and we devise techniques for calculations within string theory. Machine learning is used to help navigate our way through the huge number of spacetime geometries that string theory offers.3. Both known and proposed new theories of fundamental interactions often involve regimes where the underlying particles interact strongly. This is the case, for example, for the well established theory of the strong force, quantum chromodynamics. The regime of strong interactions is one where it is challenging to relate the characteristics of the underlying theory to potential experimental observations, and part of our effort is devoted to devising methods to better understand the consequences of strongly-interacting theories, both within string theory, which offers numerous frameworks to study strong interactions, as well as with a view to phenomenological applications.4. We also put considerable effort into making predictions for theories that are weakly interacting. This is especially important in order to draw conclusions from the high-precision data about the Higgs boson and other particles being studied at CERN's LHC. The basic principles for how to make predictions for weakly interacting theories are well established, however putting them into practice brings huge challenges, which we attempt to address through novel mathematical, computational and physics approaches.