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，以及所有这些如何适应我们在宇宙中观察到的情况。我们有一个非常好的理论来描述许多粒子和相互作用的所有这一切（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，我们的知识存在很大的漏洞，这给我们的研究小组留下了工作机会。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（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原子核进行数学建模的巧妙方法：Skyrme 模型。现在，我们可以使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其背后的数学：它与引力理论和弦理论（模拟粒子微弱量子环的数学理论）有关。除原子核外，还有其他强束缚的粒子，例如 B 介子。为此，必须构建复杂的计算机程序，将空间和时间分解为点网格，并使用该网格上的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计算机上获得的数字与实验数据相匹配。我们将开发这些计算，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）混合的水平。这有助于准确描述无法解释的现象：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。弦理论是一个数学极其丰富的结构，旨在描述引力。它的一种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。这些微小环路的行为就像粒子一样，除非我们以我们当前实验无法达到的高能量来探测它们。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的相互作用概率之间存在严格的关系。有时，通过将一种弦理论映射到另一种弦理论，可以更容易地理解诸如此类的真理，而另一种弦理论具有不同的耦合强度和不同数量的时空维度。这些“对偶性”帮助我们揭示弦理论中的真理和深层联系。我们将研究它们在交互概率之间的关系中的作用。 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，如果超对称性保持希格斯光（这是 LHC 能够发现的超对称性的主要动机），LHC 应该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，其他一些粒子或相互作用也应该负责消除量子涨落（粒子的沸腾随机质量突然出现和消失），这往往会使希格斯质量重约 10^15 倍比大型强子对撞机刚刚观察到的还要多。这些粒子也应该很快就会被发现。我们将解释数据，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

具有理论不确定性的部分子分布的首次确定

DOI：
10.1140/epjc/s10052-019-7364-5
发表时间：
2019-05-10
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：
Michael Wilson

Parton distributions with theory uncertainties: general formalism and first phenomenological studies NNPDF Collaboration

具有理论不确定性的帕顿分布：一般形式主义和第一个现象学研究 NNPDF 协作