Electroweak parton shower for high-energy particle collisions

在像LHC这样的高能对撞机上，对粒子反应的电弱修正在远高于电弱标度的能量范围内变得越来越重要，在TeV能量范围内达到10%。占主导地位的电弱修正与电弱规范玻色子的交换或发射有关，具有普遍的起源。虽然主要的虚拟修正是以解析形式在单圈和双圈水平上已知的，并且大多包括在预测中(至少在单圈水平上)，但由重粒子发射引起的实际修正通常被忽略或留给实验者用前序蒙特卡罗产生器进行的背景计算。本项目的目标是开发一个完整的弱电弱部分子簇射，它以一种与过程无关的方式模拟大质量粒子的发射，并在多功能蒙特卡罗事件发生器Sherpa中实现。通过对基于簇射的截面预测和基于全矩阵元素的截面预测的详细比较，将适当地验证簇射。此外，还将通过改变簇射的起始比例、后坐方案和结束条件来考察簇射的内在精度。该项目将提高理论预测的准确性和我们对对撞机过程的电弱修正的理解，将有益于粒子物理学的理论和实验界，并将有助于将理论预测推向全球百分比精度。

Electroweak corrections to particle reactions at high-energy colliders such as the LHC become increasingly important at energies well above the electroweak scale and reach several 10% in the TeV energy range. The dominant electroweak corrections are connected to the exchange or emission of electroweak gauge bosons and are of universal origin. While the leading virtual corrections are known at the one- and two-loop level in analytic form and mostly included in predictions (at least at the one-loop level), the real corrections induced by heavy-particle emission are most often neglected or left to background calculations carried out by experimentalists with leading-order Monte Carlo generators. This project aims at the development of a complete electroweak parton shower, which simulates massive-particle emission in a process-independent way, and the implementation of the shower in the multi-purpose Monte Carlo event generator SHERPA. The shower will be properly validated by detailed comparisons of cross-section predictions based on the shower on the one hand and on full matrix elements on the other. Moreover, the intrinsic precision of the shower will be investigated by varying the starting scale, the recoil scheme, and the ending condition of the shower. This project will improve the accuracy of theoretical predictions and our understanding of electroweak corrections to collider processes, will be beneficial to both the theory and experimental communities in particle physics, and will contribute to push theoretical predictions towards global percent accuracy.