Template Overlap Method for Massive Jets

TL;DR

The paper introduces template overlaps, a new class of infrared safe jet observables that effectively distinguish highly boosted particle decays from QCD backgrounds, showing promising results with potential for systematic improvements.

Contribution

The paper presents the novel concept of template overlaps as infrared safe jet observables for boosted decay identification, with initial testing demonstrating strong background rejection capabilities.

Findings

Good rejection power for boosted top and Higgs decays

Effective discrimination when combined with jet shape cuts

Potential for systematic improvement with higher order corrections

Abstract

We introduce a new class of infrared safe jet observables, which we refer to as template overlaps, designed to filter targeted highly boosted particle decays from QCD jets and other background. Template overlaps are functional measures that quantify how well the energy flow of a physical jet matches the flow of a boosted partonic decay. Any region of the partonic phase space for the boosted decays defines a template. We will refer to the maximum functional overlap found this way as the template overlap. To illustrate the method, we test lowest-order templates designed to distinguish highly-boosted top and Higgs decays from backgrounds produced by event generators. For the functional overlap, we find good results with a simple construction based on a Gaussian in energy differences within angular regions surrounding the template partons. Although different event generators give different averages for our template overlaps, we find in each case excellent rejection power, especially when combined with cuts based on jet shapes. The template overlaps are capable of systematic improvement by including higher order corrections in the template phase space.