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arXiv · 2510.02225

Constraints on new physics from decays of polarized $\Lambda_b^0$ baryons at the FCC-ee

Anja Beck·Mero Elmarassy·Asher Sabbagh·Michal Kreps·Eluned Smith
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Abstract

The $Z^0$ bosons produced in electron-positron collisions at the potential Future Circular Collider (FCC-ee) provide unique opportunities for flavour physics. The non-zero polarization of \Lb baryons produced in $Z^0$ decays enables access to a much larger set of observables than at the LHC, where the $\Lambda_b^0$ baryons are produced unpolarized. This paper presents a toy angular analysis of $\Lambda_b^0\to \Lambda(\to p\pi^-)\mu^+\mu^-$ 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 $C_{9^{(\prime)}}$ and $C_{10^{(\prime)}}$.

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Anja Beck, Mero Elmarassy, Asher Sabbagh, Michal Kreps, Eluned Smith. 2025-10-02. Constraints on new physics from decays of polarized $\Lambda_b^0$ baryons at the FCC-ee. https://doi.org/10.1103/tx1d-vyqk

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