QCD-aware partonic jet clustering for truth-jet flavour labelling

TL;DR

This paper introduces a QCD-aware jet clustering algorithm for assigning partonic flavour labels to truth jets in simulations, improving robustness and portability over existing methods.

Contribution

The paper presents a novel jet clustering algorithm that incorporates QCD and QED rules for more accurate and systematic partonic flavour labelling in Monte Carlo simulations.

Findings

Algorithm is portable across major shower generators.

Largely insensitive to systematic variations.

Contamination from multi-parton scattering can affect results.

Abstract

We present an algorithm for deriving partonic flavour labels to be applied to truth particle jets in Monte Carlo event simulations. The inputs to this approach are final pre-hadronization partons, to remove dependence on unphysical details such as the order of matrix element calculation and shower generator frame recoil treatment. These are clustered using standard jet algorithms, modified to restrict the allowed pseudojet combinations to those in which tracked flavour labels are consistent with QCD and QED Feynman rules. The resulting algorithm is shown to be portable between the major families of shower generators, and largely insensitive to many possible systematic variations: it hence offers significant advantages over existing ad hoc labelling schemes. However, it is shown that contamination from multi-parton scattering simulations can disrupt the labelling results. Suggestions are made for further extension to incorporate more detailed QCD splitting function kinematics, robustness improvements, and potential uses for truth-level physics object definitions and tagging.