Investigations of particles, quantum fields and extended objects

我们感兴趣的是最小的物质发生了什么，它们是如何相互作用的，力到底是什么，以及这一切如何与我们在宇宙中观察到的东西相吻合。我们有一个很好的理论来描述这一切对于许多粒子和相互作用（量子场论）。总的来说，测量结果与预测相符，这是一项重大的科学成就。然而，我们的知识有很大的漏洞，这为我们的研究小组的工作留下了机会。例如，原子核位于原子的中心。原子核是紧密结合的，这意味着我们不知道如何使用标准技术（用笔和纸）分析计算任何东西。我们的研究发现了一种利用分析技术对核进行数学建模的聪明方法：Skyrme模型。现在，我们可以用这个模型来描述原子序数从1到108的所有原子核。我们将更详细地探索这背后的数学：它与引力理论和弦理论（模拟粒子在量子环上运动的数学理论）有关。除了原子核之外，还有其他一些粒子是强束缚的，比如b介子。为此，必须建立复杂的计算机程序，将空间和时间分解成点网格，并使用该网格上的随机数模拟亚核相互作用的量子涨落。为了使计算机上得到的数字与实验数据相符，必须进行分析计算。我们将发展这些计算，并执行新的计算，以便数据可以用于提取各种夸克（例如，上夸克和b夸克）混合的水平。这有助于准确描述一种无法解释的现象：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。弦理论是一个数学上非常丰富的结构，旨在描述引力。它的一种变体甚至可能是在自然界中观察到的所有粒子之间相互作用的基础。这些微小的环路表现得像粒子，除非有人以我们目前实验无法达到的高能量探测它们。我们的一些研究考察了这些理论数学背后的丰富结构：结果表明，散射两个粒子和散射三个粒子在相互作用概率之间有严格的关系。有时，通过将一个弦理论映射到另一个弦理论，这样的事实更容易理解，因为另一个弦理论具有不同的耦合强度和不同数量的时空维度。这些“二象性”帮助我们找出弦理论的真相和深层联系。我们将研究它们在相互作用概率之间的关系中的作用。大型强子对撞机将在2015年左右关闭后重新启动，其能量是2012年的两倍。这意味着，如果超对称保持了高对称性（这是大型强子对撞机能够发现的那种超对称的主要动机），大型强子对撞机应该会在运行的第一年发现超对称粒子。即使这种超对称的想法在自然界中不存在，一些其他的粒子或相互作用应该负责抵消量子涨落（一种突然出现和消失的粒子的随机质量），这种涨落往往使希格斯粒子的质量比刚刚在大型强子对撞机上观察到的要重10^15倍。这些粒子也将很快被发现。我们将解释这些数据，并通过将各种模型的预测与大型强子对撞机看到的任何信号进行比较来区分它们。我们应该能够找出哪些理论是被排除在外的，哪些是受欢迎的。

We are interested in what is happening to the smallest bits of matter, howthey interact with each other, what a force really is, and how all of thisfits into what we observe around us in the universe. We have a very goodtheory that describes all this for many of the particles and interactions(quantum field theory). By and large, themeasurements line up with the predictions and this is a significant scientificachievement. However, there are large holes in our knowledge and this leavesoppurtunity for work by our research group.For instance, in the centre of atoms lies the nucleus. The nucleus is stronglybound, which means that we don't know how to calculate anything analytically(with a pen and paper) using the standard techniques. Our research has found a clever way of mathematically modelling the nucleususing analytic techniques: the Skyrme model. Now, we can describe all nucleifrom atomic number 1 to 108 using this model. We shall be exploring themathematics behind this in more detail: it has a connection to gravitationaltheories and string theories (mathematical theories that model particles astiny quantum loops). There are also other particles other than nuclei whichare strongly bound, such as B-mesons. For these, sophisticated computer programs must bebuilt 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 thesecalculations, and perform new ones so that data can be used to extract thelevel 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 alsohelp the extraction of the difference between matter and anti-matter fromexperimental data. String theory is an extraordinarily mathematically rich structure, thatpurports to describe gravity. One variant of it may also even underlie all ofthe interactions between particles that are observed in nature. The tiny loopsbehave like particles unless one probes them at energies that are far too highfor us to reach in current experiments. Some of our research examines the richstructure behind the mathematics of these theories: it turns out thatscattering two particles and scattering three particles have strict relationsbetween the interaction probabilities. Sometimes, truths such as these areeasier understood by mapping one string theory to another one, which has adifferent coupling strength and a different number of space-timedimensions. These "dualities" help us winkle out truths anddeep connections in string theory. We shall be investigating their role in therelations between interaction probabilities. The LHC will start up again after the shut-down around 2015 with double theenergy that it had in 2012. This means that if supersymmetry keeps the higgslight (this is the main motivation for the kind of supersymmetry that the LHCcan discover), the LHC should discover supersymmetric particles in the firstyear of running. Even if this idea of supersymmetry is not present in nature,some other particles or interactions should be responsible for cancelling thequantum fluctuations (a seething random mass of particles popping in and outof existence) which tend to make the Higgs mass some 10^15 times heavier thanhas just been observed at the LHC. These particles should also be discoveredsoon. We shall be interpreting the data, and discriminating various models bycomparing their predictions to any signals that the LHC sees. We should beable to work out which theories are ruled out, and which are favoured.