reSolve — A transverse momentum resummation tool

In this note, we introduce the new tool reSolve, a Monte Carlo differential cross-section and parton-level event generator whose main purpose is to add transverse momentum resummation to a general class of inclusive processes at hadron colliders, namely all those which do not involve hadrons or jets in the measured final state. This documentation refers to the first main version release, which will form the basis for continued developments, consequently it only implements the key features of those we plan to ultimately include. This article acts as a manual for the program; describing in detail its use, structure, validation and results; whilst also highlighting key aspects of the resummation formalism applied. It details the two classes of processes so far included; these are diphoton production and Drell–Yan production.

A main concept behind the development of the tool is that it is a hands-on white box for the user: significant effort has been made to give the program a modular structure, making the various parts which comprise it independent of each other as much as possible and ensuring they are transparently documented, customisable and, in principle, replaceable with something that may better serve the user’s needs.

reSolve is a new C++ program, based on an evolution of the private Fortran code 2gres, it is also influenced by the DYRes Fortran code. This initial version calculates the low transverse momentum contribution to the fully differential cross-section for two main categories of processes; the inclusive production of two photons, and inclusive Drell–Yan production. In all cases resummation up to Next-to-Next-to-Leading Logarithm (NNLL) is included. We aim to extend the program to several more processes in the near future. The program is publicly available on Github.

在本篇笔记中，我们介绍了新工具reSolve，该工具为蒙特卡洛微分截面及部分子级事件生成器，其核心目的是为强子对撞机中一类通用的全事件过程添加横向动量重整化，具体而言，是指所有不涉及强子或喷注在测量最终状态中的过程。本文档针对首次主要版本发布进行说明，它将构成持续发展的基础，因此它仅实现了我们计划最终包含的关键特性。本文档充当程序手册，详细阐述了程序的使用、结构、验证和结果；同时，也突出了所应用的重整化公式的关键方面。它详细描述了迄今为止包含的两类过程；这些是双光子产生和Drell-Yan产生。工具开发背后的主要理念是它为用户提供了一个直观的白盒工具：为使程序具有模块化结构，我们付出了显著的努力，使其组成部分尽可能独立，并确保其透明化、可定制以及原则上可用满足用户需求的其他工具替换。reSolve是一个新的C++程序，基于对私有Fortran代码2gres的演进，同时也受到DYRes Fortran代码的影响。此初始版本计算了低横向动量贡献至全微分截面的两个主要类别过程；两个光子的全事件产生以及Drell-Yan的全事件产生。在所有情况下，均包含至次次领对数（NNLL）的重整化。我们计划在不久的将来将该程序扩展到更多过程。该程序可在GitHub上公开获取。