Identifying Boosted Objects with N-subjettiness

TL;DR

This paper introduces N-subjettiness, a new jet shape variable that effectively identifies boosted hadronically-decaying particles like W bosons and top quarks, improving background rejection and discovery potential.

Contribution

The paper presents N-subjettiness as a novel jet shape variable that enhances boosted object tagging and background discrimination in high-energy physics analyses.

Findings

Achieves 30% tagging efficiency with 1% fake rate for boosted W bosons and top quarks.

Significantly improves discovery potential for heavy resonances decaying into boosted objects.

Combines advantages of jet shapes and substructure algorithms for better discrimination.

Abstract

We introduce a new jet shape -- N-subjettiness -- designed to identify boosted hadronically-decaying objects like electroweak bosons and top quarks. Combined with a jet invariant mass cut, N-subjettiness is an effective discriminating variable for tagging boosted objects and rejecting the background of QCD jets with large invariant mass. In efficiency studies of boosted W bosons and top quarks, we find tagging efficiencies of 30% are achievable with fake rates of 1%. We also consider the discovery potential for new heavy resonances that decay to pairs of boosted objects, and find significant improvements are possible using N-subjettiness. In this way, N-subjettiness combines the advantages of jet shapes with the discriminating power seen in previous jet substructure algorithms.