Helac-Phegas: A generator for all parton level processes

Abstract
The updated version of the Helac-Phegas^1 1URL: http://www.cern.ch/helac-phegas. event generator is presented. The matrix elements are calculated through Dyson-Schwinger recursive equations using color connection representation. Phase-space generation is based on a multichannel approach, including optimization. Helac-Phegas generates parton level events with all necessary information, in the most recent Les Houches Accord format, for the study of any process within the Standard Model in hadro...

Title of program: HELAC-PHEGAS
Catalogue Id: ADMS_v2_0

Nature of problem
One of the most striking features of final states in current and future colliders is the large number of events with several jets. Being able to predict their features is essential. To achieve this, the calculations need to describe as accurately as possible the full matrix elements or the underlying hard processes. Even at leading order, perturbation theory based on Feynman graphs runs into computational problems, since the number of graphs contributing to the amplitude grows as n!.

Versions of this program held in the CPC repository in Mendeley Data
ADMS_v1_0; HELAC; 10.1016/S0010-4655(00)00151-X
ADMS_v2_0; HELAC-PHEGAS; 10.1016/j.cpc.2009.04.023

This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)

摘要
本文介绍了Helac-Phegas（Helac-Phegas）事件生成器的更新版本^1。^1 访问链接：http://www.cern.ch/helac-phegas。其矩阵元通过采用色连接表象的戴森-施温格（Dyson-Schwinger）递归方程进行计算。相空间生成基于包含优化步骤的多通道方法实现。Helac-Phegas可生成符合最新莱斯胡契协定（Les Houches Accord）格式的部分子层次事件，并附带所有必要信息，用于研究标准模型（Standard Model）中强子hadro...范围内的任意过程。

程序名称：HELAC-PHEGAS
目录编号：ADMS_v2_0

问题本质
当前及未来对撞机的末态最显著的特征之一，便是包含多个喷注的事件数量极为庞大。准确预测这些事件的特征至关重要。为实现这一目标，计算需要尽可能精准地描述完整矩阵元或核心硬散射过程。即便在领头阶（leading order）时，基于费恩曼图（Feynman graphs）的微扰理论便会遭遇计算瓶颈，因为贡献于散射振幅的费恩曼图数量随n!指数增长。

存放在Mendeley Data中的CPC程序库内的该程序版本：
ADMS_v1_0; HELAC; 10.1016/S0010-4655(00)00151-X
ADMS_v2_0; HELAC-PHEGAS; 10.1016/j.cpc.2009.04.023

本程序源自贝尔法斯特女王大学（Queen's University Belfast）维护的CPC程序库（1969-2019）。