On jet substructure methods for signal jets

TL;DR

This paper analyzes the effects of QCD radiation on jet substructure methods for boosted Higgs decay jets, proposing improvements and optimal parameters to enhance tagging performance at high transverse momentum.

Contribution

It provides analytical and Monte Carlo insights into jet substructure taggers, introducing a combined Y-splitter and trimming method that outperforms existing techniques.

Findings

Y-splitter performance improved with trimming

Combined tagger outperforms individual methods at high pT

Analytical estimates align with Monte Carlo results

Abstract

We carry out simple analytical calculations and Monte Carlo studies to better understand the impact of QCD radiation on some well-known jet substructure methods for jets arising from the decay of boosted Higgs bosons. Understanding differences between taggers for these signal jets assumes particular significance in situations where they perform similarly on QCD background jets. As an explicit example of this we compare the Y-splitter method to the more recently proposed Y-pruning technique. We demonstrate how the insight we gain can be used to significantly improve the performance of Y-splitter by combining it with trimming and show that this combination outperforms the other taggers studied here, at high $p_T$. We also make analytical estimates for optimal parameter values, for a range of methods and compare to results from Monte Carlo studies.