Calculation of higher order corrections for TeV colliders

我们目前对物质组成的理解总结在所谓的基本粒子物理学标准模型（SM）中。这个模型已经在过去的几十年里在世界各地的几个高能粒子对撞机上建立和测试。然而，这个模型的一个组成部分，希格斯玻色子，仍然缺失。此外，有理论上的理由相信，SM只是一个有效的理论，在低能量的一个更基本的基础理论背后。这些理论的候选者是超对称性、超引力或具有超过四维时空的弦理论。为了找到希格斯玻色子并找到更基本的理论，必须研究比过去实验更高能量的粒子碰撞。为此，欧洲核子研究中心（日内瓦）建造了一个大型强子对撞机（LHC），在那里两个质子被引导碰撞，每个质子都有足够的能量产生希格斯玻色子，如果标准模型假设是正确的。然而，为了从大量的“无趣的”碰撞（称为“背景”）中提取这样的希格斯粒子产生事件（称为“信号”），对信号和背景事件的精确计算和模拟是必要的。这种计算是拟议研究的主题。为了达到所需的精度，并尽可能接近地模拟实验环境，必须计算所谓的“辐射校正”。在过去几年中，已经建立了一些用于这种计算的技术，但仅用于非常有限的一类过程，即仅检测到少数处于最终状态的粒子的过程。对于多粒子生产，计算相当复杂，需要开发新的方法，主要基于强大的计算机资源。此外，还计划建立一个国际正负电子直线对撞机，在那里可以进行非常高能量的前所未有的精确测量，以便更多地了解应该在大型强子对撞机上发现的新粒子的性质，并找到迄今为止无法检测到的粒子。为了使理论预测具有这种机器所需的精度，辐射校正的计算必须进一步推进。拟议的项目将对产生三个所谓“喷流”的过程进行非常精确的理论预测，这些喷流是通过强相互作用结合在一起的粒子团。这种计算将能够以前所未有的精度测量强耦合常数，并为其他过程的高精度预测打开大门。总之，该项目旨在构建高度自动化的程序，以便对未来高能对撞机产生的大量数据进行精确的理论预测。

Our current understanding about the constituents of matter is summarized in the so-called Standard Model (SM) of Elementary Particle Physics. This model has been established and tested over the past decades at several high energy particle colliders around the world. However, one ingredient of this model, the Higgs boson, is still missing. Further, there are theoretical reasons to believe that the SM is only an effective theory at low energies of a more fundamental underlying theory behind. Candidates for such theories are supersymmetry, supergravity or string theories/theories with more than four space-time dimensions. To find the Higgs boson and to find out about a more fundamental theory, particle collisions at higher energies than in past experiments have to be investigated. To this aim, a Large Hadron Collider (LHC) is built at CERN (Geneva) where two protons are lead to collision, each having an energy which will be sufficient to produce Higgs bosons if the Standard Model assumptions are right. However, in order to extract such Higgs production events (called 'signals') from the huge amount of 'uninteresting' collisions (called 'background'), precise calculations and simulations of the signal as well as the background events are necessary. Such calculations are subject of the proposed research. In order to achieve the required precision and to simulate the experimental environment as close as possible, so-called 'radiative corrections' have to be calculated. Some techniques for such calculations already have been established over the last years, but only for a very limited class of processes, i.e. processes where only few particles in the final state are detected. For multi-particle production, the calculations are quite involved and require the development of new methods, largely based on powerful computer resources. Further, an international electron-positron Linear Collider is planned where measurements of an unseen precision at very high energy can be performed in order to learn more about the properties of the new particles which should be discovered at the LHC and to find particles which could not be detected so far.. In order to make theoretical predictions with a precision needed for such a machine, the calculation of radiative corrections has to be pushed even further. The proposed project will lead to a very precise theoretical prediction for a process where three so-called 'jets' are produced, which are clusters of particles bound together by strong interactions. This calculation will enable the measurement of the strong coupling constant with an unprecedented precision and also open the door to high precision predictions for other processes. In summary, the project aims at the construction of highly automated programs in order to make precise theoretical predictions for the wealth of data which will be produced at future high energy colliders.