Getting a flavour for New Physics with precision measurements of tree-level beauty decays

基本粒子物理学有一个令人难以置信的成功的基本理论框架，被称为标准模型，它在最近几十年里产生了一系列成功的预测和随后的发现。这在2012年发现希格斯玻色子时达到了顶峰，希格斯玻色子是标准模型中最后一个缺失的部分。然而，仍然有许多观测到的现象是标准模型无法解释的，本研究的重点是理解宇宙的物质-反物质不对称性。在炎热的早期宇宙中，物质和反物质应该是等量产生的；这是通过爱因斯坦著名的方程E=mc^2将能量转化为物质的简单过程。一旦宇宙冷却，物质和反物质就会“湮灭”，留下大量的电磁辐射。我们今天看到的电磁辐射是宇宙微波背景辐射，在未调谐的电视上看到的静态辐射。然而，显然存在一种不平衡，因为我们也看到了大量的物质，这些物质构成了恒星、星系和我们自己，而反物质却一点也没有留下。我们可以将其部分理解为由于电荷宇称对称（将物质与反物质联系起来）被打破。在物质-反物质创造的初始阶段，电荷宇称的破坏导致了少量的物质过剩，这些物质继续构成了今天的可观测宇宙，在大多数物质与反物质湮灭之后，留下的电磁辐射仍然在宇宙周围回荡。问题是，根据我们对基本粒子物理学的理解，理论框架所预测的电荷宇称违反的数量远不足以解释宇宙中观测到的物质与电磁辐射的比例（差了几十亿倍）。这个项目使用大型强子对撞机的数据来寻找新的基本物理粒子，这些粒子可以帮助解释物质-反物质的差异。通过分析在LHCb实验中产生的数百万个物质和反物质衰变，我们可以观察到它们之间的细微差别。我们在这个项目中确定的参数特别有趣，因为它们可以完全独立于理论框架的任何输入进行测量，即独立于任何先验知识。然后，我们可以用这些参数来证明存在，并预测新的基本物理粒子的行为，这些粒子解释了为什么我们生活在一个物质主导的宇宙中，因此为什么我们有原子、分子和生命本身。

Elementary particle physics has an incredibly successful underlying theoretical framework known as the Standard Model which has produced a succession of successful predictions and subsequent discoveries in recent decades. This culminated in the discovery of the Higgs Boson in 2012, which was the last missing piece of the Standard Model. However, there are still a multitude of observed phenomena which the Standard Model cannot explain and the focus of this research is understanding the matter-antimatter asymmetry of the universe. In the hot early universe matter and antimatter should have been created in equal amounts; this is the simple conversion of energy into matter via Einstein's famous equation, E=mc^2. Once the universe cooled the matter and antimatter would have "annihlated" to leave behind an abundance of electromagnetic radiation. This electromagnetic radiation we see today as the cosmic microwave background, the static seen on an untuned televsion. However, there is clearly an imbalance as we also see large amounts of matter, which make up the stars, galaxies and ourselves whilst no antimatter is left at all. We can understand some part of this as being due to charge-parity symmetry (that which relates matter to antimatter) being broken. In the intial stages of matter-antimatter creation charge-parity violation results in a small excess of matter, which goes on to make up the observable universe of today, after the majority annihilates with the antimatter to leave behind the electromagnetic radiation still echoing around the universe. The problem is that the amount of charge-parity violation predicted by the theoretical framework underlying our understanding of elementary particle physics is nowhere near enough (a factor several billion off) to account for the observed matter to electromagnetic radiation ratio of the universe. This project uses data from the Large Hadron Collider to look for new fundamental physics particles which can help to explain the matter-antimatter discrepancy. By analysing millions of matter and antimatter decays produced at the LHCb experiment we can observe the subtle differences between them. The parameters we determine in this project are of particular interest because they can be measured completely independently of any input from the theoretical framework, i.e. independently of any prior knowledge. We can then use these parameters to prove the existence, and predict the behaviour, of new fundamental physics particles which explain why we live in a matter dominated universe and hence why we have atoms, molecules and life itself.