Quantum Fields, Quantum Gravity and Quantum Particles

剑桥大学理论高能物理组的STFC研究项目主要关注对撞机现象学、量子场论和量子引力的基本问题，并分析一类称为强子的强相互作用粒子。我们将通过计算来理解存在的基本原理，以及我们对宇宙和宇宙中物质的理解。这些努力大部分都支持粒子物理学在欧洲核子研究中心和其他地方的实验，以及对宇宙的天体物理学和宇宙学观测中，为了解释一些实验数据并从中学习我们所能学到的一切，需要深入量子理论的技术性、困难性和详细的计算。质子（在大型强子对撞机上碰撞的粒子）的结构将得到更好的理解，以便对碰撞进行可靠的预测。我们正在分析和解释来自CERN的大型强子对撞机数据，以做各种事情：寻找新粒子或力的迹象，为它们开发搜索和测量策略，或对各种理论进行高精度预测。标准模型是粒子物理学中被广泛接受、验证和测量的现行模型。它的大部分预测与对撞机数据吻合得很好。然而，它留下了许多疑问：为什么基本粒子在质量上有特殊的模式？我们将根据目前的数据建立数学模型，试图解释一些这样的特征，同时提供实验测试。我们也在忙碌着为未来的科学家们提供支持，研究他们能很好地回答哪些问题。引力在小距离尺度下的行为在理论上是如何理解的，尽管弦理论可能是理解它的一个有趣的框架。我们将在数学上发展和研究量子引力理论，以推动理解。黑洞为计算提供了一个特别的焦点：这些物体周围的引力非常强，我们将从它们的理论研究中学到很多东西。弦理论新发展中的各种计算对这一点很重要，对如何计算粒子散射的发展也很重要。弦理论将被构造出来，看看它们与我们所看到的宇宙有多接近。此外，我们还将研究、发展暴胀模型（宇宙早期经历极端快速膨胀的时期），并将其与观测结果进行比较。有些粒子，如强子，是较小粒子的强束缚态。为此，建立了复杂的计算机程序，将空间和时间分解成网格点，并使用该网格上的随机数模拟亚核相互作用的量子涨落。必须进行分析计算，使计算机上得到的数据与实验数据相吻合。我们将发展这些计算，并执行新的计算，以便可以使用数据来提取各种夸克（例如，上夸克和b夸克）混合的能级。这有助于准确描述一个无法解释的现象：夸克混合的有趣模式是如何产生的。这些计算也有助于从实验数据中提取物质和反物质之间的差异。我们可以预测哪些强束缚态可能存在及其性质，而对实验中看到的更奇特和更令人困惑的变体的研究将是一个重要的工作途径。

The STFC research programme of the Theoretical High Energy Physics Group atCambridge University is focused on the fundamental problems of colliderphenomenology, quantum field theory and quantum gravity, and analysing aclass of strongly interacting particles called hadrons.In this research, weshall perform calculations to understand the fundamentals underlyingreality and our understanding of the universe and matter within it. Much of this effort supports particle physics experiments at CERN andelsewhere, as well as astrophysical and cosmological observations of theuniverse.Technical, difficult, and detailed calculations deep in quantum theory arerequired in order to interpret some of the experimental data and to learneverything we can from them. The structure of the proton (the particlesthat collided at the Large Hadron Collider) will be understood better in order to getrobust and reliable predictions on the collisions. We are analysingand interpreting Large Hadron Collider data from CERN to do various things: looking for signs of new particles or forces, developingsearch and measurement strategies for them, or making high precisionpredictions of various theories. The Standard Model is the current model ofparticle physics that is well accepted, verified, and measured. Most of itspredictions agree well with collider data. However, it leaves many questionsunanswered: why do the fundamental particles have the particular pattern theydo in their masses? We shall be developing mathematical models, based oncurrent data, to try to explain some such features, and provide experimentaltests at the same time. We are also busy supporting the science case for futurecolliders, investigating which questions they could answer well.How gravity behaves at small distance scales is badly understoodtheoretically, although string theory may be an interesting framework forunderstanding it.We will be developing and investigating theories of quantumgravity mathematically in order to push the understanding forward.Blackholes provide a particular focus for the calculations: these are objectsaround which gravity is very strong, and we will learn much from theirtheoretical study. Variouscalculations in new developments of string theory are important for this, andfor the development of how to calculate particle scattering in general. String theories will be constructed to see how close they come to the universewe see. Also, models of inflation (a time in the early universe when theuniverse underwent extremely rapid expansion) will be investigated, developed, and compared with observations.Some particles, such as hadrons, are strongly bound states of smaller ones. For these, sophisticated computer programs are built which break space and time up into a grid of points, and the quantumfluctuations of the sub-nuclear interactions are simulated using randomnumbers on this lattice. Analytic calculations must be done to match thenumbers obtained on the computer to experimental data. We shall develop these calculations, and perform new ones so that data can be used to extract the level to which various quarks (for example, the up quark and the b-quark) mix. This helps provide an accurate description of an unexplained phenomenon: how the funny pattern of quark mixing comes about. These calculations also help the extraction of the difference between matter and anti-matter from experimental data. We can predict much about which strongly bound states may exist and their properties, and studies of the more exotic and puzzling varieties seen in experiments will be an important avenue of work.