The mass area of jets

TL;DR

This paper introduces the concept of jet mass area to quantify how susceptible a jet's mass is to soft background contamination, providing a new tool for jet analysis and correction.

Contribution

It defines the mass area, explores its properties across various jet algorithms, and demonstrates its utility in pileup correction and jet analysis.

Findings

Mass area varies with jet algorithm and particle configuration.

Passive and active mass areas exhibit different behaviors.

Mass area can be used to correct jets for pileup contamination.

Abstract

We introduce a new characteristic of jets called mass area. It is defined so as to measure the susceptibility of the jet's mass to contamination from soft background. The mass area is a close relative of the recently introduced catchment area of jets. We define it also in two variants: passive and active. As a preparatory step, we generalise the results for passive and active areas of two-particle jets to the case where the two constituent particles have arbitrary transverse momenta. As a main part of our study, we use the mass area to analyse a range of modern jet algorithms acting on simple one and two-particle systems. We find a whole variety of behaviours of passive and active mass areas depending on the algorithm, relative hardness of particles or their separation. We also study mass areas of jets from Monte Carlo simulations as well as give an example of how the concept of mass area can be used to correct jets for contamination from pileup. Our results show that the information provided by the mass area can be very useful in a range of jet-based analyses.