Reconstructing the invisible with matrix elements

TL;DR

This paper introduces a flexible hypothesis testing method using the Matrix Element Method to distinguish signal from background in processes with multiple invisible particles, demonstrated on Higgs decay.

Contribution

It presents a novel approach that maps measured final states onto a minimal hypersurface and maximizes matrix elements for signal and background separation.

Findings

Effective separation of signal and background demonstrated

Method applicable to complex processes with invisible particles

Improved hypothesis testing accuracy in particle physics

Abstract

We propose a fully flexible method to perform an hypothesis test between signal and background based on the Matrix Element Method in the presence of multiple invisible particles. The proposed method performs a mapping of the measured final state onto its minimal hypersurface of degrees of freedom for a given process and then maximises the matrix element on this hypersurface separately for signal and background. To show how performant the method is in separating signal from background, we apply it to the prominent partly invisible decay of a Higgs boson into a muon-antimuon pair and two muon-neutrinos via two W bosons.