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宇宙作为一个整体的最大尺度与最小的基本粒子尺度联系起来。斯旺西粒子物理和宇宙学理论小组致力于一系列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以及量子场和弦理论的基本方面的理解相关的问题。人们普遍认为，早期宇宙经历了一段快速膨胀的时期，称为通货膨胀。然而，关于宇宙膨胀的机制以及与量子引力理论的可能联系，仍有许多悬而未决的问题，这一理论尚未定义。一个诱人的问题是，是否可以探测到由膨胀引起的引力波，这导致了引力波宇宙学的领域。暗物质和暗能量的性质可能为了解早期宇宙提供了一个额外的窗口，可以检查量子引力、超引力和弦理论的观测结果和预期之间的一致性。黑洞和霍金辐射仍然是试图调和量子力学和引力的灵感来源。使用量子信息中熟悉的概念，对纠缠和量子关联的详细理解在这里提供了新的见解。碰撞的黑洞和两个量子点粒子进行量子引力散射的计算似乎完全不同，这两个粒子之间的新数学等价将提供关于引力波发射的补充信息。描述上述一切的框架结合了量子场论、几何学和引力。理论进展探索了二元性、全息学和几何学，将迄今无关的理论联系在一起，并揭示了M理论的新结构，M理论是重力、弦和场的首要概念。在基本粒子的尺度上，强子是由夸克和胶子形成的。在当前和未来的粒子对撞机上，新发现的奇异强子以及夸克和胶子在新物质相中的性质，如夸克-胶子等离子体，正在进行严格的研究。要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，例如在具有高重数的多循环过程的情况下。重离子碰撞实验通过短暂地重现早期宇宙中普遍存在的条件，探索了轻强子不复存在的QCD[量子色动力学]转变。重离子碰撞的现象学需要对QCD光谱如何随温度变化进行定量预测。由于QCD的强耦合性质，需要使用现有的最大的超级计算机来依赖数值方法。与机器学习的新联系可能会在这里提供丰硕的成果，将数据生成和解释方面的知识从该社区转移到计算粒子物理。反过来，来自计算粒子物理学的洞察力可能会揭示ML在从大型数据集学习和生成具有所需特征的集合方面尚未解释的成功。了解QCD以外的强耦合动力学将建模文献与探索标准模型以外的物理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、顶层复合性、强相互作用暗物质，以及可能更具推测性的早期宇宙现象，在某些情况下，这些现象可以在大型强子对撞机上进行测试。