The Matrix Element Method at next-to-leading order accuracy

TL;DR

This paper extends the Matrix Element Method to next-to-leading order accuracy, enabling more precise extraction of parameters like the top-quark mass from experimental data.

Contribution

It introduces an efficient NLO calculation method for event weights and demonstrates its application to top-quark mass measurement in e+e- collisions.

Findings

Significant differences between LO and NLO results in top-quark mass extraction

The new method improves the precision of the MEM at NLO accuracy

Potential impact on interpreting top-quark mass measurements at colliders

Abstract

The Matrix Element Method (MEM) has proven beneficial to make maximal use of the information available in experimental data. However, so far it has mostly been used in Born approximation only. In this paper we discuss an extension to NLO accuracy. As a prerequisite we present an efficient method to calculate event weights for jet events at NLO accuracy. As illustration and proof of concept we apply the method to the extraction of the top-quark mass in e+e- annihilation. We observe significant differences when moving from LO to NLO which may be relevant for the interpretation of top-quark mass measurements at hadron colliders relying on the MEM.