Double Parton Scattering at the LHC and Beyond

大部分关于改进质子-质子碰撞理论预测的工作都集中在改进最高能量的“初级”部分子-部分子碰撞的描述上。然而，额外的部分子-部分子碰撞可以并且确实发生。在单个质子-质子碰撞中有两个高能部分子-部分子碰撞的情况称为双部分子散射（DPS）。这个过程可以在某些运动学区域和/或某些过程中与单次散射的速率竞争，揭示了质子结构的新信息，并且随着对撞机能量的增长变得更加重要。这个项目的目的是开发工具，使预测DPS的基础上，第一次，第一原理QCD理论。这项工作的一个主要组成部分将是进一步发展的蒙特卡罗模拟DPS，dShower -例如，包括某些量子相关效应，强子化，和不等尺度过程。然后，这些工具将被应用于预测关键的LHC过程，其中DPS可以发挥重要作用，如同号WW，多重重口味和4喷气生产过程。本研究的一个重要目标是找到完整QCD框架的预测与先前使用的简化DPS模型所获得的预测不同的测量-这些差异将由部分子间相关性和仅存在于前者的QCD效应引起，并且都是实验上固有的有趣搜索，以及重要的是要知道的DPS背景的准确描述，以其他搜索。在这个项目的最终目标将是提高DPS预测的非微扰建模，通过结合所有已知的信息，从理论约束，晶格计算和实验所产生的DPS的非微扰部分。

Most of the work on improving theoretical predictions for proton-proton collisions has focussed on improving the description of the highest-energy "primary" parton-parton collision. However, additional parton-parton collisions can and do occur. The case in which we have two high-energy parton-parton collisions in an individual proton-proton collision is known as double parton scattering (DPS). This process can compete in rate with single scattering in certain kinematic regions and/or for certain processes, reveals new information on proton structure, and becomes more important as collider energy grows. The aim of this project is to develop tools to make predictions for DPS that are based, for the first time, on first principles QCD theory. A major component of this work will be the further development of the Monte Carlo simulation of DPS, dShower - for example, to include certain quantum correlation effects, hadronisation, and unequal scale processes. These tools will then be applied to make predictions for key LHC processes where DPS can play an important role, such as the same-sign WW, multiple heavy flavour and 4 jet production processes. An important goal in this study will be to find measurements where the predictions of the full QCD framework differ from those obtained by the simplified DPS models used previously - these differences will be caused by inter-parton correlations and QCD effects present only in the former, and are both intrinsically interesting to search for experimentally, as well as being important to know for the accurate description of DPS backgrounds to other searches. A final goal in this project will be to improve the nonperturbative modelling in DPS predictions, by combining all known information about the nonperturbative part of DPS arising from theoretical constraints, lattice calculations, and experiment.