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Exact baryon-meson relation for $b \to s ν \bar{ν}$

Teppei Kitahara ^1,2,*, Manas Kumar Mohapatra ^3,†, and Kota Sasaki ^1,‡

¹Department of Physics, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
²Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Furo-cho Chikusa-ku, Nagoya 464-8602, Japan
³School of Physics, University of Hyderabad, Hyderabad 500046, India

^*Contact author: kitahara@chiba-u.jp
^†Contact author: manasmohapatra12@gmail.com
^‡Contact author: sasaki@chiba-u.jp

Phys. Rev. D 114, 075019 – Published 13 October, 2026

DOI: https://doi.org/10.1103/19ml-r53z

Abstract

We derive an exact relation among the normalized branching fractions of $Λ_{b} \to Λ ν \bar{ν}$ and $B \to K^{(*)} ν \bar{ν}$ , within the lepton-number-conserving effective Hamiltonian in which only active neutrinos contribute to the invisible final state. Although the effective Hamiltonian contains 18 independent Wilson coefficients, the three normalized rates depend on only two independent combinations of them, leading to an exact algebraic relation. Remarkably, the central values of the coefficients of this baryon-meson relation are close to $1 / 4$ and $3 / 4$ , which appear in the heavy-to-heavy $b \to c$ semileptonic sum rule among the branching fractions of $Λ_{b} \to Λ_{c} τ \bar{ν}$ and $B \to D^{(*)} τ \bar{ν}$ . Once the decay rate of $B \to K^{*} ν \bar{ν}$ is measured, the decay rate of $Λ_{b} \to Λ ν \bar{ν}$ can be determined in a model-independent manner for new-physics scenarios involving only active neutrino interactions, thereby providing a clean target prediction for future experiments. This clearly demonstrates that observables in baryonic and mesonic $b \to s ν \bar{ν}$ transitions will serve as a compact consistency test and a powerful probe for discriminating among new-physics scenarios.

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References (79)

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Phys. Rev. D 114, 075019– Published 13 October, 2026

Vol. 114, Iss. 7 — 1 October 2026

Received 28 April 2026
Accepted 25 September 2026

DOI: https://doi.org/10.1103/19ml-r53z

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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Exact baryon-meson relation for $b \to s ν \bar{ν}$

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Exact baryon-meson relation for b→sνν¯

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Exact baryon-meson relation for $b \to s ν \bar{ν}$