Identifying a new particle with jet substructures

TL;DR

This paper explores how jet substructure techniques can be used to identify properties of a heavy resonance decaying into electroweak gauge bosons, enhancing particle detection and characterization at high energies.

Contribution

It introduces a novel application of jet substructure and matrix element methods to improve the identification of heavy resonances decaying into Z bosons in collider experiments.

Findings

Jet substructure enhances the discrimination power of kinematic observables.

Matrix element methods with jet substructure can effectively identify the nature of the resonance.

The approach is robust across different jet sizes and grooming parameters.

Abstract

We investigate a potential of measuring properties of a heavy resonance X, exploiting jet substructure techniques. Motivated by heavy higgs boson searches, we focus on the decays of X into a pair of (massive) electroweak gauge bosons. More specifically, we consider a hadronic Z boson, which makes it possible to determine properties of X at an earlier stage. For $m_X$ of O(1) TeV, two quarks from a Z boson would be captured as a "merged jet" in a significant fraction of events. The use of the merged jet enables us to consider a Z-induced jet as a reconstructed object without any combinatorial ambiguity. We apply a conventional jet substructure method to extract four-momenta of subjets from a merged jet. We find that jet substructure procedures may enhance features in some kinematic observables formed with subjets. Subjet momenta are fed into the matrix element associated with a given hypothesis on the nature of X, which is further processed to construct a matrix element method (MEM)-based observable. For both moderately and highly boosted Z bosons, we demonstrate that the MEM with current jet substructure techniques can be a very powerful discriminator in identifying the physics nature of X. We also discuss effects from choosing different jet sizes for merged jets and jet-grooming parameters upon the MEM analyses.