Flavoured jet algorithms - a comparative study

Finally, me and collaborators published a work that has been in the making since the PhysTeV workshop 2023. It focuses on a key challenge for experiments at particle colliders like the Large Hadron Collider (LHC): accurately identifying “heavy-flavour jets.”

A jet is a narrow spray of particles that is created when a high-energy quark or gluon is produced in a particle collision. A heavy-flavour jet is specifically one that originates from a bottom or charm quark. The accurate identification of these jets is crucial for understanding the fundamental principles of the Standard Model of particle physics and for searching for new particles or forces.

The paper evaluates new methods, called “flavoured jet algorithms,” which are designed to address a technical problem known as infrared and collinear (IRC) safety. This issue can cause inconsistencies between theoretical calculations and experimental measurements. By comparing these new algorithms with the methods currently used at the LHC, we found that while the new algorithms lead to more consistent results, their performance varies.

Flavoured jet algorithms: a comparative study

Authors: Arnd Behring, Simone Caletti, Francesco Giuli, Radoslaw Grabarczyk, Andreas Hinzmann, Alexander Huss, Joey Huston, Ezra D. Lesser, Simone Marzani, Davide Napoletano, Rene Poncelet, Daniel Reichelt, Alberto Rescia, Gavin P. Salam, Ludovic Scyboz, Federico Sforza, Andrzej Siodmok, Giovanni Stagnitto, James Whitehead, Ruide Xu

Abstract: The accurate identification of heavy-flavour jets, those which originate from bottom or charm quarks, is crucial for precision studies of the Standard Model and searches for new physics. However, assigning flavour to jets presents significant challenges, primarily due to issues with infrared and collinear (IRC) safety. This paper aims to address these challenges by evaluating recently-proposed jet algorithms designed to be IRC-safe and applicable in high-precision measurements. We compare these algorithms across benchmark heavy-flavour production processes and kinematic regimes that are relevant for LHC phenomenology. Exploiting both fixed-order calculations in QCD as well as parton shower simulations, we analyse the infrared sensitivity of these new algorithms at different stages of the event evolution and compare to flavour-labelling strategies currently adopted by LHC collaborations. The results highlight that, while all algorithms lead to more robust flavour-assignments compared to current techniques, they vary in performance depending on the observable and energy regime. The study lays groundwork for robust, flavour-aware jet analyses in current and future collider experiments to maximise the physics potential of experimental data by reducing discrepancies between theoretical and experimental methods.

Article on arxiv.org