The matrix element method at next-to-leading order for arbitrary jet algorithms

TL;DR

This paper extends the matrix element method to next-to-leading order for arbitrary infrared-safe jet algorithms, enabling more precise theoretical predictions in particle physics analyses.

Contribution

It introduces three variants of the NLO matrix element method applicable to arbitrary jet algorithms, including a fixed-order and POWHEG-inspired approaches.

Findings

Developed a method for integrating over radiation phase space at NLO.

Presented variants compatible with arbitrary infrared-safe jet algorithms.

Enhanced the precision of matrix element method calculations at NLO.

Abstract

The matrix element method usually employs leading-order matrix elements. We discuss the generalisation towards higher orders in perturbation theory and show how the matrix element method can be used at next-to-leading order for arbitrary infrared-safe jet algorithms. We discuss three variants at next-to-leading order. The first two variants work at the level of the jet momenta. The first variant adheres to strict fixed-order in perturbation theory. We present a method for the required integration over the radiation phase space. The second variant is inspired by the POWHEG method and works as the first variant at the level of the jet momenta. The third variant is a more exclusive POWHEG version. Here we resolve exactly one jet into two sub-jets. If the two sub-jets are resolved above a scale $p_\bot^{\mathrm{min}}$, the likelihood is computed from the POWHEG-modified real emission part, otherwise it is given by the POWHEG-modified virtual part.