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arXiv · 2603.15461

Probing the neutrino mass through semileptonic meson decays

Damir Bečirević·Claire Chevallier·Svjetlana Faifer·Nejc Košnik·Lovre Pavičić
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Abstract

We argue that a detailed analysis of semileptonic decays can test the possibility of a massive neutrino. The key observable, related to the forward-backward asymmetry, is exactly zero for a massless neutrino but becomes non-zero if the neutral lepton is heavy and interacts with Standard Model fields via left-handed operators. For right-handed interactions, this quantity differs significantly from zero even for a massless right-handed neutrino. We demonstrate this explicitly using the example of a pseudoscalar meson decaying into another pseudoscalar meson. A similar discussion applies to decays into a vector meson, with an additional subtlety addressed in this work.

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Damir Bečirević, Claire Chevallier, Svjetlana Faifer, Nejc Košnik, Lovre Pavičić. 2026-03-16. Probing the neutrino mass through semileptonic meson decays. https://doi.org/10.1103/793f-29kk

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