Particles, Fields and Extended Objects

剑桥大学理论高能物理小组的STFC研究计划集中在碰撞现象学、量子场论、弦理论和引力等基本问题上，并分析一类被称为强子的强相互作用粒子。在这项研究中，我们将进行计算，以了解现实背后的基本原理，以及我们对宇宙和其中物质的理解。这项工作的大部分工作支持欧洲核子研究中心和其他地方的粒子物理实验，以及对宇宙的天体物理和宇宙学观测。为了解释一些实验数据，并从中学到任何我们能从中学到的东西，需要深入量子理论的技术、困难和详细的计算。质子(在大型强子对撞机上碰撞的粒子)的结构将被更好地理解，以便获得关于碰撞的可靠和可靠的预测。我们正在分析和解释来自欧洲核子研究中心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，或者对各种理论进行高精度预测。标准模型是目前被广泛接受、验证和测量的粒子物理模型。它的大部分预测与对撞机数据吻合得很好。然而，它留下了许多问题没有得到回答：为什么基本粒子在它们的质量中有它们所具有的特殊图案？我们将根据当前的数据开发数学模型，试图解释一些这样的特征，同时提供实验测试。我们还忙于支持未来对撞机的科学案例，调查他们可以很好地回答哪些问题。虽然弦理论可能是理解它的一个有趣的框架，但从理论上很难理解引力在小距离尺度上的表现。我们将从数学上发展和研究量子引力理论，以推动理解。黑洞为计算提供了特别的焦点：这些物体周围的引力非常强大，我们将从他们的理论研究中学到很多东西。弦理论的新发展中的变分计算对于这一点以及对如何计算粒子散射的一般发展来说都是重要的。弦理论将被构建来观察它们与我们所看到的宇宙有多近。此外，还将研究、开发膨胀模型(宇宙经历极快膨胀的早期宇宙)，并与观测结果进行比较。一些粒子，如强子，是较小粒子的强束缚状态。为此，人们建立了复杂的计算机程序，将空间和时间分解成一个点阵，并在这个点阵上使用随机数来模拟亚核相互作用的量子涨落。必须进行分析计算，以使在计算机上获得的数值与实验数据相匹配。我们将发展这些计算，并执行新的计算，以便数据可以用来提取各种夸克(例如，上夸克和b夸克)混合到的能级。这有助于准确地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。这些计算还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，以及它们的性质，而对实验中看到的更奇异和令人费解的变种的研究将是一项重要的工作。

The STFC research programme of the Theoretical High Energy Physics Group atCambridge University is focused on the fundamental problems of colliderphenomenology, quantum field theory, string theory and 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 the 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 particlescollided 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, developedand 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 experiment will be an important avenue of work.