RapidSim: An application for the fast simulation of heavy-quark hadron decays

RapidSim is a lightweight application for the fast simulation of phase space decays of beauty and charm quark hadrons, allowing for quick studies of the properties of signal and background decays in particle physics analyses. Based upon the TGenPhaseSpace class from the ROOT application it uses externally provided fixed-order next-to-leading-logarithm calculations to boost the initial beauty and charm hadrons to the appropriate energy for the production environment of interest. User-defined momentum resolution functions can be used to mimic the effect of imperfect track reconstruction. User-defined efficiency shapes can be applied during generation to reproduce the effects of geometric and kinematic requirements on final state particles as well as the dynamics of the decay. The effect of mis-identification of the final state particles is simple to configure via configuration files, while the framework can easily be extended to include additional particle types. This paper describes the RapidSim framework, features and some example use cases.

RapidSim是一款轻量级应用，用于快速模拟美夸克与粲夸克强子的相空间衰变，可支持粒子物理分析中对信号衰变及本底衰变特性的快速研究。该工具基于ROOT软件中的TGenPhaseSpace类，调用外部提供的固定阶次次领头对数（fixed-order next-to-leading-logarithm）计算结果，将初始美、粲强子提升至目标产生环境所需的适宜能量。用户可自定义动量分辨函数，以模拟不完善径迹重建带来的影响；还可在生成过程中应用自定义的效率分布函数，复现末态粒子的几何与运动学选择要求，以及衰变动力学的效应。末态粒子的误标识效应可通过配置文件便捷配置，同时该框架可轻松扩展以纳入更多粒子类型。本文介绍了RapidSim框架的构成、核心特性以及若干典型应用案例。