Electroweak parton shower for high-energy particle collisions

在诸如大型强子对撞机这样的高能对撞机中，对粒子反应的电弱修正在远高于电弱尺度的能量范围内变得越来越重要，在TeV能量范围内达到10%。主要的电弱修正与电弱规范玻色子的交换或发射有关，并且具有普遍的起源。虽然领先的虚拟修正在分析形式的一环和双环水平上是已知的，并且主要包括在预测中（至少在一环水平上），但由重粒子发射引起的实际修正通常被忽略，或者留给实验家使用领先的蒙特卡罗发生器进行的背景计算。本项目旨在开发一个完整的电弱部分子阵雨，以独立于过程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中实现该阵雨。通过详细比较一方面基于阵雨的截面预测和另一方面基于全矩阵元素的截面预测，将适当地验证阵雨。此外，还将通过改变阵雨的启动尺度、后坐力方案和结束条件来研究阵雨的内在精度。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，将有利于粒子物理学的理论和实验社区，并将有助于推动理论预测达到全球百分比的准确性。

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.