Determination of the top-quark mass from top-quark pair events with the matrix element method at next-to-leading order: Potential and prospects

In 2004 the matrix element method was used in a pioneering work by the Tevatron experiment D/0 to determine the top-quark mass from a handful of events. Since then the method has matured into a powerful analysis tool. While the first applications were restricted to leading-order accuracy, the extension to next-toleading order (NLO) accuracy has also been studied. In this article we explore the potential of the matrix element method at NLO to determine the top-quark mass using events with pair-produced top quarks. We simulate a toy experiment by generating unweighted events with a fixed input mass and apply the matrix element method to construct an estimator for the top-quark mass. Two different setups are investigated; unweighted events obtained from the fixed-order cross section at NLO accuracy as well as events obtained using POWHEG matched to a parton shower. The latter lead to a more realistic simulation and allow to study the impact of higher-order corrections as well as the robustness of the approach. We find that the matrix element method in NLO accuracy leads to a significant reduction of the theoretical uncertainties compared to leading order. In view of the high-luminosity phase of the LHC, this observation is especially relevant in analyses which are no longer dominated by statistical uncertainties.

Automated summary

In 2004, the matrix element method was used by the D/0 experiment at the Tevatron to determine the top-quark mass, and it has since become a powerful analysis tool. This article explores the potential of using the matrix element method at NLO to determine the top-quark mass using pair-produced top quark events. The study finds that the NLO accuracy significantly reduces theoretical uncertainties compared to leading order.