On the Treatment of Resonances in Next-to-Leading Order Calculations Matched to a Parton Shower

TL;DR

This paper introduces a new subtraction method for next-to-leading order calculations that effectively handles resonances and is compatible with parton shower generators, improving the accuracy of simulations involving narrow resonances.

Contribution

A novel subtraction technique for NLO calculations that includes finite width effects and resonance interferences, integrated into the POWHEG BOX framework.

Findings

Successfully implemented in POWHEG BOX

Handles finite width effects and interferences

Validated with single top production process

Abstract

In this work we present a new subtraction method for next-to-leading order calculations that is particularly convenient even when narrow resonances are present. The method is particularly suitable for the implementation of next-to-leading order calculations matched to parton shower generators. It allows at the same time for the inclusion of all finite width effects, including interferences, and for a consistent treatment of resonances in the shower approach, preserving the mass of resonances near their peak. We implement our method, in a fully general and automatic way, within the POWHEG BOX framework, and illustrate it using as a test case the process of $p p \to \mu^+ \nu_\mu j_b j$, that is dominated by $t$-channel single top production.