Improving new physics searches with precision: Sudakov logarithms up to the two-loop level

精确改进新的物理搜索：苏达科夫对数达到二环水平

• 批准号: 2488818
• 金额: --
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2488818
• 关键词: Improving; new; physics; searches; precision

A major aim of the ongoing experiments at the Large Hadron Collider (LHC) is the hunt for phenomena beyond the Standard Model (SM). These phenomena are extremely hard to come by - very small event rates for new physics processes are typically swamped by enormous backgrounds due to SM interactions. In fact, without a clear sign of new physics in terms of new resonances, we are required to look for very small percent-level deviations in the tails of distributions measured in very complex final states. Experimentally, percent-level precision will be achievable in the near future. However, matching this remarkable precision in theory predictions is a true challenge that requires to incorporate higher-order corrections in perturbation theory. At hadron colliders like the LHC we are primarily concerned with higher-order QCD corrections in order to improve our theoretical modelling. However, far above the electroweak (EW) scale higher-order EW corrections are strongly enhanced due to the appearance of Sudakov logarithms, which are universal and generated by well-defined structures of the contributing loop amplitudes at a given perturbative order. These corrections can easily reach a similar level as QCD higher-order corrections at hadron colliders. Thanks to recent advances in the automation of next-to-leading order EW corrections any SM process up to high particle multiplicity can now be evaluated including EW corrections. In order to further improve the predictions and in particular to arrive at reliable uncertainty estimates of the EW corrections the project at hand should develop an automated implementation of the Denner-Pozzorini algorithm for the calculation of EW Sudakov logarithms up to the two-loop level. As a first step the implementation of one-loop EW Sudakov logarithms should be foreseen, which is already available in the literature and can thus easily be validated. The implementation relies on the factorization of EW Sudakov logarithms with respect to the Born process valid up to the next-to-next-to logarithmic order. Once the described implementation is available phenomenological studies will be performed exploiting the newly archive precision and control of theoretical uncertainties. In particular this will concern the production of vector bosons in the vector-boson-fusion and vector-boson-scattering topologies, which both allow for stringent indirect searches for new physics.

大型强子对撞机（LHC）正在进行的实验的一个主要目标是寻找超越标准模型（SM）的现象。这些现象是非常难以获得的-非常小的事件率为新的物理过程通常淹没了巨大的背景，由于SM相互作用。事实上，在没有新物理学在新共振方面的明确迹象的情况下，我们需要在非常复杂的终态中测量的分布的尾部中寻找非常小的π能级偏差。从实验上看，在不久的将来将可以实现1000级的精度。然而，在理论预测中匹配这种显著的精度是一个真正的挑战，需要在微扰理论中引入高阶修正。在强子对撞机，如大型强子对撞机，我们主要关注高阶QCD修正，以改善我们的理论模型。然而，远高于电弱（EW）规模的高阶EW校正强烈增强，由于外观的Sudakov双稳态，这是普遍的，并产生了明确的结构，在一个给定的扰动顺序的贡献环振幅。这些修正可以很容易地达到与强子对撞机上的QCD高阶修正相似的水平。由于最近的进展，自动化的次领先的顺序EW校正任何SM过程，以高粒子的多重性，现在可以评估，包括EW校正。为了进一步改进预测，特别是为了得到可靠的电子战修正的不确定性估计，手头的项目应该开发一个自动执行的Denner-Pozzorini算法，用于计算高达两个回路的电子战Sudakov矩阵。作为第一步，应预见单回路电子战Sudakov系统的实施，这在文献中已经有了，因此可以很容易地验证。该实施依赖于EW Sudakov矩阵的因式分解相对于玻恩过程有效的下一个到下一个对数阶。一旦所描述的实现是可用的现象学研究将利用新的档案精度和控制理论的不确定性。特别是，这将涉及矢量玻色子融合和矢量玻色子散射拓扑结构中矢量玻色子的产生，这两种拓扑结构都允许对新物理进行严格的间接搜索。