Reducing negative weights in Monte Carlo event generation with Sherpa

TL;DR

This paper reviews the origin of negative weights in high-precision Monte Carlo event generators and presents methods to reduce their occurrence in Sherpa simulations, improving computational efficiency for particle physics analyses.

Contribution

It introduces mechanisms to decrease negative weight fractions in Sherpa's S-MC@NLO simulations, enhancing the practicality of high-accuracy event generation.

Findings

Reduced negative weight fractions in V+jets and tt+jets simulations

Improved computational efficiency in Monte Carlo event generation

Enhanced accuracy in particle physics simulations

Abstract

An increase in theoretical precision of Monte Carlo event generators is typically accompanied by an increased need for computational resources. One major obstacle are negative weighted events, which appear in Monte Carlo simulations with higher perturbative accuracy. While they can be handled somewhat easily in fixed-order calculations, they are a major concern for particle level event simulations. In this article, the origin of negative weights in the S-MC@NLO method is reviewed and mechanisms to reduce the negative weight fraction in simulations with the Sherpa event generator are presented, with a focus on V+jets and tt+jets simulations.