Precision studies of the Higgs boson decay channel H -> ZZ -> 4l with MEKD

TL;DR

This paper evaluates the matrix element method's effectiveness in analyzing the Higgs boson decay to four leptons, emphasizing interference effects and providing a computational tool for improved property measurements.

Contribution

It introduces MEKD, a code for calculating kinematic discriminants using full matrix elements, enhancing analysis of the H -> ZZ -> 4l channel.

Findings

Proper treatment of interference effects improves sensitivity.

Matrix element method effectively discriminates signal from background.

MEKD aids in studying Higgs properties with better accuracy.

Abstract

The importance of the H -> ZZ -> 4l "golden" channel was shown by its major role in the discovery, by the ATLAS and CMS collaborations, of a Higgs-like boson with mass near 125 GeV. We analyze the discrimination power of the matrix element method both for separating the signal from the irreducible ZZ background and for distinguishing various spin and parity hypotheses describing a signal in this channel. We show that the proper treatment of interference effects associated with permutations of identical leptons in the four electron and four muon final states plays an important role in achieving the best sensitivity in measuring the properties of the newly discovered boson. We provide a code, MEKD, that calculates kinematic discriminants based on the full leading order matrix elements and which will aid experimentalists and phenomenologists in their continuing studies of the H -> ZZ -> 4l channel.