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Flavor-physics benchmarks for tracker-based particle identification at the FCC-ee

Department of Physics and Laboratory for Nuclear Science, MIT, Cambridge, Massachusetts 02139, USA

^*Contact author: anbeck@mit.edu

Phys. Rev. D 113, 072016 – Published 28 April, 2026

DOI: https://doi.org/10.1103/lnx2-s8wb

Abstract

The correct identification of charged hadrons plays a crucial role in flavor-physics measurements. The final detector configurations at the proposed Future Circular Collider are yet to be determined and this study aims to contribute to this discussion by benchmarking the particle-identification (PID) performance of the proposed CLD and IDEA detectors using fully simulated events. At present, neither detector proposal includes dedicated PID systems, relying instead on information from the tracking subsystems. We estimate the expected level of contamination due to misidentified charged hadrons for $b$ -flavor tagging, rare $b \to s$ transitions, and $s$ -jet tagging. The PID information provided by silicon trackers, namely time-of-flight and energy-deposit measurements, leads to significant background suppression with high signal efficiency for the low-momentum hadrons considered for same-side $b$ -flavor tagging. In order to improve the contamination in rare decays where momenta are in the medium range, only good timing resolution of 30 ps and below can yield an improvement of one order of magnitude below the level achieved by kinematic criteria alone. Light-quark jet-flavor tagging requires identification of particles with very large momentum, which is not possible using only time-of-flight or energy-deposit information in silicon. Access to the number of clusters in a drift-chamber setup, as proposed for the IDEA detector, however, results in strong background suppression in every case. This suppression can be further improved in some scenarios by time-of-flight resolution of 30–50 ps or better. The PID quality generally exhibits only a small dependence on the cluster-counting efficiency. Whether dedicated PID detectors could further enhance flavor-physics sensitivity should be the subject of future study.

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Phys. Rev. D 113, 072016– Published 28 April, 2026

Vol. 113, Iss. 7 — 1 April 2026

Received 5 December 2025
Accepted 19 March 2026

DOI: https://doi.org/10.1103/lnx2-s8wb

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Flavor-physics benchmarks for tracker-based particle identification at the FCC-ee

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