Theoretical Particle Physics and Cosmology

理论粒子物理和宇宙学

• 批准号: ST/X000648/1
• 负责人: Timothy Hollowood
• 金额: $ 198.53万
• 依托单位: Swansea University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FX000648%2F1
• 关键词: Theoretical; Particle; Physics; Cosmology

Research in particle physics and cosmology connects the largest scales, those of the Universe as a whole, with the smallest, namely those of fundamental particles. The Swansea Particle Physics and Cosmology Theory group works on a wide range of problems relevant for our understanding of cosmology and gravitational waves, black holes, the physics of the Standard Model and beyond the Standard Model, and fundamental aspects of quantum field and string theory. It is commonly understood that the early Universe underwent a period of rapid expansion, called inflation. However, many open questions remain, on the mechanism of cosmological inflation and on possible links to the theory of quantum gravity, which is yet to be defined. A tantalising question is whether gravitational waves arising from inflation can be detected, leading to the field of gravitational wave cosmology. The nature of dark matter and dark energy may provide an additional window into the early universe, with consistency checks between observations and expectations from quantum gravity, supergravity and string theory. Black holes and Hawking radiation remain a source of inspiration in attempts to reconcile quantum mechanics with gravity. A detailed understanding of entanglement and quantum correlations provides new insights here, using concepts familiar from quantum information. A new mathematical equivalence between colliding black holes and seemingly completely different calculations of two quantum point particles undergoing quantum gravitational scattering will give complementary information on gravitational wave emission. The framework to describe all of the above combines quantum field theory, geometry and gravity. Theoretical advances explore dualities, holography and geometry, linking hitherto unrelated theories and uncovering new structures in M-theory, the overarching concept of gravity, strings and fields. At the scale of elementary particles, hadrons are formed out of quarks and gluons. Properties of newly discovered 'exotic' hadrons and of quarks and gluons in new phases of matter, such as the quark-gluon plasma, are under intense investigation at current and future particle colliders. To obtain full scientific value from the wealth of data generated by the Large Hadron Collider requires high-precision theoretical predictions, e.g. in the case of multi-loop processes at high multiplicity. Heavy-ion collision experiments probe the QCD [Quantum Chromodynamics] transition at which light hadrons cease to exist, by briefly recreating conditions prevalent in the early universe. The phenomenology of heavy-ion collisions requires quantitative predictions on how the QCD spectrum changes with temperature. Due to the strongly coupled nature of QCD, numerical methods need to be relied on, using the largest supercomputers available. A new connection with Machine Learning may provide fruitful here, transferring knowledge on data generation and interpretation from that community to computational particle physics. In reverse, insight from computational particle physics may shed light on the yet unexplained success of ML, in learning from large data sets and generating ensembles with desirable features. Understanding strongly-coupled dynamics beyond QCD links the model-building literature with phenomenological and experimental international programmes probing physics beyond the Standard Model, covering a range of extensions including Composite Higgs models, top compositeness, strongly-interacting dark matter, and possibly more speculative early-universe phenomena, which in some cases are testable at the Large Hadron Collider.

粒子物理学和宇宙学的研究将最大的尺度（整个宇宙的尺度）与最小的尺度（即基本粒子的尺度）联系起来。斯旺西粒子物理学和宇宙学理论小组致力于研究与我们对宇宙学和引力波，黑洞，标准模型和超越标准模型的物理学以及量子场和弦理论的基本方面有关的广泛问题。人们通常认为，早期宇宙经历了一段快速膨胀的时期，称为暴胀。然而，许多悬而未决的问题仍然存在，关于宇宙膨胀的机制以及与量子引力理论的可能联系，这尚未被定义。一个诱人的问题是，暴胀产生的引力波是否可以被探测到，从而引出引力波宇宙学领域。暗物质和暗能量的性质可能会为早期宇宙提供一个额外的窗口，并在量子引力，超引力和弦理论的观测和预期之间进行一致性检查。黑洞和霍金辐射仍然是试图调和量子力学与引力的灵感来源。对纠缠和量子关联的详细理解在这里提供了新的见解，使用量子信息中熟悉的概念。碰撞黑洞和两个量子点粒子经历量子引力散射的看似完全不同的计算之间的一个新的数学等价性将提供引力波发射的补充信息。描述上述所有内容的框架结合了量子场论、几何学和引力。理论的进步探索了对偶性、全息术和几何学，将迄今为止不相关的理论联系起来，并揭示了M理论的新结构，M理论是引力、弦和场的总体概念。在基本粒子的尺度上，强子是由夸克和胶子形成的。新发现的“奇异”强子和新物质相（如夸克胶子等离子体）中夸克和胶子的性质正在当前和未来的粒子对撞机上进行深入研究。为了从大型强子对撞机产生的大量数据中获得充分的科学价值，需要高精度的理论预测，例如在高多重性的多回路过程中。重离子碰撞实验通过简单地重现早期宇宙中普遍存在的条件来探测QCD [量子色动力学]跃迁，在QCD跃迁处轻强子不再存在。重离子碰撞的现象学需要对QCD谱随温度的变化进行定量预测。由于QCD的强耦合性质，需要依靠数值方法，使用最大的超级计算机。与机器学习的新联系可能会在这里产生成果，将数据生成和解释的知识从该社区转移到计算粒子物理学。相反，来自计算粒子物理学的见解可能会揭示ML在从大型数据集学习和生成具有理想特征的集合方面尚未解释的成功。理解QCD之外的强耦合动力学将模型建立文献与探索标准模型之外的物理学的现象学和实验国际计划联系起来，涵盖了一系列扩展，包括复合希格斯模型，顶部复合，强相互作用暗物质，以及可能更具投机性的早期宇宙现象，在某些情况下可以在大型强子对撞机上进行测试。