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Investigations in Theoretical Particle Physics

理论粒子物理研究

基本信息

批准号：
ST/G000581/1
负责人：
Nicholas Stephen Manton
金额：
$ 380.35万
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：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FG000581%2F1
关键词：
Investigations Theoretical Particle Physics

项目摘要

The Large Hadron Collider (LHC) will start operating this year, colliding protons at much greater energies than ever achieved before. Through Einstein's famous equation $E=mc^2$, this greater energy can be turned into the masses of heavier particles than ever seen before. Hints from experiments a decade ago suggest that at least the Higgs particle, or something very like it, should be produced at LHC. The Cambridge group are developing techniques to extract the few Higgs particles' signature decays from the billions upon billions of other particles produced. We shall study how to extract properties of the Higgs particle from the data, including its spin, which theorists have predicted to be zero. Building accurate computer simulations of the collisions and subsequent decays is one important activity. In our current theories, the Higgs particle is responsible for the origin of the mass of all other fundamental particles, but it is a puzzle why the Higgs is not far heavier still. Speculative ideas such as supersymmetry, or extra space dimensions, can solve the puzzle, but we cannot believe in these unless their effects are unambiguously measured. One possible effect is the production of particles of dark matter at the LHC, whose signature is 'missing energy' in the particle collision. We shall need to investigate any dark matter signatures and check whether they are compatible with our theories of the early universe. Analysing data is difficult because many of the particles produced are complicated lumps of more fundamental particles, the quarks, stuck together by the strong nuclear force. Indeed, the initial protons colliding at the LHC are like this. There is no easy way to calculate what happens in this 'sticking together' process, and special mathematical techniques have to be developed. This is an important focus of our work at Cambridge. In some of our theories the equations have a lot of hidden symmetry that can be teased-out and exploited; in others we can approximate space-time by a set of discrete points and do calculations on computers. One problem we want to solve is how protons and neutrons themselves stick together in the nuclei of atoms. We are developing approximate theories in which the shapes of nuclei come out as solutions of the equations. Even if the Higgs and supersymmetry were to be discovered, there remain many mysteries in particle physics. For example, how does gravity fit into particle physics? Mathematically, gravity leads to inconsistencies in particle theories at distance scales much smaller than the size of a proton, possibly because space-time itself becomes fuzzy through quantum fluctuations. String theory, with its tiny curled-up extra dimensions, offers our best hope of a mathematically consistent solution. Much of the group's effort will go into further investigating, checking and developing the mathematical structure of string theory. String theories partly predict what new particles might be discovered at the LHC. These predictions emerge when one tries to build explicit stringy theories incorporating the particles we already know about. Known particles place constraints on the shape of the curled-up extra dimensions, and this is very interesting mathematically. We shall be considering the effects of all this on our understanding of the universe as a whole. For instance, string theory has interesting consequences for 'bounce' solutions of the universe where it continually collapses and re-expands, smoothing out the big bang singularity through quantum mechanics. This, and alternative models of the universe, will be tested against measurements of the after-glow of the big bang -- the Cosmic Microwave sky -- and the increasingly accurate measurements of the amount of 'dark energy' and 'dark matter' in the universe.

大型强子对撞机(LHC)将于今年开始运行，碰撞质子的能量比以往任何时候都大得多。通过爱因斯坦著名的方程$E=mc^2$，这种更大的能量可以转化为比以往任何时候都更重的粒子质量。十年前的实验暗示，至少应该在大型强子对撞机上产生希格斯粒子，或者非常类似的粒子。剑桥研究小组正在开发从产生的数十亿其他粒子中提取少数几个希格斯粒子的特征衰变的技术。我们将研究如何从数据中提取希格斯粒子的属性，包括它的自旋，理论家预测它的自旋为零。对碰撞和随后的衰变建立准确的计算机模拟是一项重要的活动。在我们目前的理论中，希格斯粒子是所有其他基本粒子质量的来源，但为什么希格斯粒子的质量并不比希格斯粒子大得多，这是一个谜。超对称性或额外空间维度等投机性想法可以解决这个难题，但我们不能相信这些想法，除非它们的影响得到明确的衡量。一种可能的影响是在大型强子对撞机上产生了暗物质粒子，其特征是在粒子碰撞中失去了能量。我们将需要研究任何暗物质信号，并检查它们是否与我们关于早期宇宙的理论相一致。分析数据很困难，因为产生的许多粒子都是更基本的粒子--夸克--的复杂结块，它们被强大的核力粘在一起。事实上，在大型强子对撞机上碰撞的初始质子是这样的。没有简单的方法来计算在这个“粘在一起”的过程中会发生什么，必须开发特殊的数学技术。这是我们在剑桥工作的一个重要重点。在我们的一些理论中，方程有许多隐藏的对称性，可以梳理出来并加以利用；在另一些理论中，我们可以通过一组离散的点来近似时空，并在计算机上进行计算。我们想要解决的一个问题是，质子和中子本身如何在原子核中粘在一起。我们正在发展近似理论，在这些理论中，原子核的形状可以作为方程的解。即使发现了希格斯粒子和超对称性，粒子物理学仍有许多谜团。例如，重力如何与粒子物理相适应？从数学上讲，引力在比质子大小小得多的距离尺度上导致粒子理论的不一致，可能是因为时空本身因量子涨落而变得模糊。弦理论，以其微小的卷曲的额外维度，为我们提供了数学上一致的解决方案的最大希望。该小组的大部分工作将用于进一步研究、检查和发展弦理论的数学结构。弦理论部分预测了大型强子对撞机上可能发现的新粒子。当一个人试图建立包含我们已经知道的粒子的显式串理论时，这些预测就会出现。已知的粒子对卷曲的额外维度的形状施加了限制，这在数学上非常有趣。我们将考虑所有这一切对我们对整个宇宙的理解的影响。例如，弦理论对宇宙的“反弹”解产生了有趣的结果，在宇宙中它不断地坍塌和重新膨胀，通过量子力学平滑了大爆炸奇点。这一模型以及其他宇宙模型将通过测量宇宙大爆炸的余辉--宇宙微波天空--以及对宇宙中暗能量和暗物质数量的日益精确的测量来检验。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Scattering amplitudes and Wilson loops in twistor space

DOI：
10.1088/1751-8113/44/45/454008
发表时间：
2011-04
期刊：
Journal of Physics A: Mathematical and Theoretical
影响因子：
0
作者：
T. Adamo;Mathew Bullimore;L. Mason;David Skinner
通讯作者：
T. Adamo;Mathew Bullimore;L. Mason;David Skinner

The FP420 R&D Project: Higgs and New Physics with Forward Protons at the LHC

DOI：
10.1088/1748-0221/4/10/t10001
发表时间：
2008-06
期刊：
Journal of Instrumentation
影响因子：
1.3
作者：
M. Albrow;R. Appleby;M. Arneodo;G. Atoian;I. Azhgirey;R. Barlow;I. Bayshev;W. Beaumont;L. Bon
通讯作者：
M. Albrow;R. Appleby;M. Arneodo;G. Atoian;I. Azhgirey;R. Barlow;I. Bayshev;W. Beaumont;L. Bon

Confinement in anti-de Sitter space

反德西特空间的限制