New Horizons in Quantum Field Theory, Particle Physics and String Phenomenology

对标准模型的理论研究为实验发现提供了基础，并有助于形成我们目前对物质本质及其相互作用的认识。随着希格斯玻色子的发现，标准模型（SM）终于得到了完善，但在我们对宇宙的理解中，仍存在着深刻而深奥的谜团。暗物质的存在需要超越SM的新物理学，而关于暗能量和引力与其他力的统一的关键问题仍未得到解决。与此同时，作为量子场论基础的数学结构还远远没有得到充分的探索；关于SM内的物质动力学，特别是在极端环境下，还有一些重要的开放性问题。利物浦的理论物理小组从三个互补的方向为新物理学的研究做出了贡献。(i)我们在标准模型内以前所未有的精度进行微扰计算。如果要在加速器实验中检测到由于新物理学而导致的观测值与SM预测的偏差，这是必不可少的。同时，我们正在利用我们的理论专长来探索标准模型的有希望的扩展，并为发现新物理学的实验发展提供信息。这些努力还得到大规模计算机计算的补充。这种非摄动方法对于解锁标准模型理论预测的某些输入是必不可少的，这超出了摄动理论的范围。目前这些输入缺乏精度，限制了实验观察的有用性。我们的模拟是最先进的，现在包括电磁修正（QED）强相互作用QCD理论。（iii）我们确定了超越标准模型（BSM）物理学在实验数据和观测中可能产生的指纹。这类工作包括使用天体物理学和宇宙学数据，例如来自暗能量调查和引力波的数据，这导致了对实验室搜索的补充限制。这伴随着对弦理论的严格研究。除了在理解量子引力方面取得进展外，我们在这个方向上的工作还为BSM模型的建立提供了信息和灵感。我们还探索了标准模型本身的未知领域：我们将研究强相互作用物质的阶段，特别是在有限密度下，我们将开始使用第一性原理计算机模拟研究量子场论中的实时动力学。一个关键的挑战是理解夸克和胶子是如何形成强子的，而强子是物质的基本组成部分。重离子碰撞火球形成强子的标准解释需要局部热平衡，这可能是合理的，也可能是不合理的。另一种解释观测结果的独特选择是一种真正的量子效应，称为纠缠，我们将努力探索它。

Theoretical investigations of the Standard Model have underpinned experimental discoveries and have been instrumental in shaping our current knowledge of the nature of matter and its interactions. At a time when the standard model (SM) has finally been completed by the discovery of the Higgs boson, deep and profound mysteries remain in our understanding of the Universe. The existence of dark matter necessitates new physics beyond the SM, and crucial issues concerning dark energy and the unification of gravity with the other forces remain unaddressed. Meanwhile, the mathematical structures that underlie quantum field theory are far from fully explored; and there are important open questions about the dynamics of matter within the SM, especially in extreme environments.The Theoretical Physics group in Liverpool is contributing to searches for New Physics from three complementary directions. (i) We carry out perturbative calculations within the standard model to an unprecedented precision. This is essential if deviations of observables from their SM predictions, occurring due to new physics, are to be detected in accelerator experiments. Concurrently, we are using our theoretical expertise to explore promising extensions of the Standard Model and to inform the development of experiments that are well placed to discover new physics. (ii) These efforts are complemented by large scale computer based calculations. This non-perturbative approach is essential for unlocking certain inputs for standard model theory predictions, which are beyond the reach of perturbation theory. The current lack of precision in these inputs limits the usefulness of experimental observations. Our simulations are state-of-the-art and are now including electro-magnetic corrections (QED) to the theory of strong interactions QCD. (iii) We determine the fingerprints that Beyond the Standard Model (BSM) physics could produce in experimental data and observations. Such work includes the use of astrophysical and cosmological data, e.g. from dark energy surveys and gravitational waves, and it leads to constraints that complement laboratory based searches. This is accompanied by rigorous studies in string theory. In addition to progressing towards an understanding of quantum gravity, our work in this direction informs and inspires BSM model building.We also explore terra incognita within the Standard Model itself: we will study the phases of strongly interacting matter in particular at finite densities, and we will embark on the study of real-time dynamics in quantum field theory using first principle computer simulations. A key challenge is to understand how quarks and gluons form hadrons, the basic building blocks of matter. The standard explanation for forming hadrons out of a heavy ion collision fireball invokes a local thermal equilibrium, which might or might not be justified. A distinctive alternative to explain observations is a genuine quantum effect called entanglement, which we will endeavour to explore.