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Investigations of particles, quantum fields and extended objects

粒子、量子场和扩展物体的研究

基本信息

批准号：
ST/L000385/1
负责人：
Benjamin Allanach
金额：
$ 138.24万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FL000385%2F1
关键词：
Investigations particles quantum fields extended

项目摘要

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.

我们感兴趣的是最小的物质发生了什么，它们如何相互作用，力到底是什么，以及所有这些如何与我们在宇宙中观察到的相吻合。我们有一个非常好的理论，它描述了所有这些粒子和相互作用（量子场论）。总的来说，这一观测结果与预测相符，这是一项重大的科学成就。然而，在我们的知识和我们的研究小组的工作中存在着巨大的漏洞。例如，原子核位于原子的中心。原子核是强束缚的，这意味着我们不知道如何使用标准技术分析计算任何东西（用笔和纸）。我们的研究已经找到了一种巧妙的方法，利用分析技术对原子核进行数学建模：Skyrme模型。现在，我们可以用这个模型来描述从原子序数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（将粒子建模为令人惊叹的量子环的数学理论）有关。除了原子核之外，还有其他粒子也是强束缚的，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网格点，并使用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，并进行新的计算，以便可以使用数据来提取各种夸克（例如，上夸克和b夸克）混合的水平。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。弦理论是一个数学上非常丰富的结构，它旨在描述引力。它的一个变体甚至可能是自然界中观察到的粒子之间所有相互作用的基础。这些微小的环的行为就像粒子，除非我们用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：事实证明，散射两个粒子和散射三个粒子之间的相互作用概率有严格的关系。有时候，通过把一个弦理论映射到另一个弦理论，就能更容易地理解这些真理，而另一个弦理论有不同的耦合强度和不同的时空尺度。这些“对偶性”帮助我们在弦理论中找出真理和深层联系。我们将研究它们在相互作用几率关系中的作用。LHC将在2015年左右关闭后再次启动，其能量是2012年的两倍。这意味着，如果超对称性保持着希格斯略（这是LHC能够发现超对称性的主要动机），LHC应该在运行的第一年就发现超对称粒子。即使这种超对称性在自然界中并不存在，其他一些粒子或相互作用也应该负责抵消量子涨落（一种沸腾的随机质量的粒子突然出现和消失），这往往会使希格斯粒子的质量比刚刚在LHC上观察到的重10^15倍。这些粒子也应该很快被发现。我们将解释这些数据，并通过将它们的预测与LHC看到的任何信号进行比较来区分各种模型。我们应该能够弄清楚哪些理论被排除，哪些理论受到青睐。

项目成果

期刊论文数量（9）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A first determination of parton distributions with theoretical uncertainties

DOI：
10.1140/epjc/s10052-019-7364-5
发表时间：
2019-05
期刊：
The European Physical Journal C
影响因子：
0
作者：
Rabah Abdul Khalek;R. Ball;S. Carrazza;S. Forte;T. Giani;Z. Kassabov;E. Nocera;R. L. Pearson;J. Rojo;L. Rottoli;M. Ubiali;C. Voisey;Michael Wilson
通讯作者：
Rabah Abdul Khalek;R. Ball;S. Carrazza;S. Forte;T. Giani;Z. Kassabov;E. Nocera;R. L. Pearson;J. Rojo;L. Rottoli;M. Ubiali;C. Voisey;Michael Wilson

Constraints on holographic multi-field inflation and models based on the Hamilton-Jacobi formalism

全息多场膨胀的约束和基于Hamilton-Jacobi形式主义的模型