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Constraints on new physics from decays of polarized $Λ_{b}^{0}$ baryons at the FCC-ee

Anja Beck ^1,*, Mero Elmarassy ¹, Asher Sabbagh ¹, Michal Kreps ², and Eluned Smith ¹

¹Department of Physics and Laboratory for Nuclear Science, MIT, Cambridge, 02139, Massachusetts, USA
²Department of Physics, University of Warwick, Coventry, CV4 7AL, West Midlands, United Kingdom

^*Contact author: anbeck@mit.edu

Phys. Rev. D 113, 055005 – Published 3 March, 2026

DOI: https://doi.org/10.1103/tx1d-vyqk

Abstract

The $Z^{0}$ bosons produced in electron-positron collisions at the potential Future Circular Collider (FCC-ee) provide unique opportunities for flavor physics. The nonzero polarization of $Λ_{b}^{0}$ baryons produced in $Z^{0}$ decays enables access to a much larger set of observables than at the LHC, where the $Λ_{b}^{0}$ baryons are produced unpolarized. This paper presents a toy angular analysis of $Λ_{b}^{0} \to Λ (\to p π^{-}) μ^{+} μ^{-}$ decays using simulation samples of collisions at the FCC-ee reconstructed using the IDEA detector concept and assuming a dataset of $6 \times 10^{12}$ $Z^{0}$ bosons. While the statistical sensitivity achieved for individual angular observables is not expected to significantly exceed that from the LHCb Upgrade II experiment, the addition of the polarized observables leads to a significant improvement of the knowledge on the Wilson coefficients $C_{9^{(')}}$ and $C_{10^{(')}}$ .

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References (42)

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Phys. Rev. D 113, 055005– Published 3 March, 2026

Vol. 113, Iss. 5 — 1 March 2026

Received 3 October 2025
Accepted 13 February 2026

DOI: https://doi.org/10.1103/tx1d-vyqk

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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Constraints on new physics from decays of polarized $Λ_{b}^{0}$ baryons at the FCC-ee

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Constraints on new physics from decays of polarized Λb0 baryons at the FCC-ee

Abstract

Physics Subject Headings (PhySH)

Article Text

References (42)

Constraints on new physics from decays of polarized $Λ_{b}^{0}$ baryons at the FCC-ee