Testing the unitarity of the light neutrino mixing matrix

Fuente: arXiv
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Main Authors: Gabrielli, E., Lind, A., Marzola, L., Müürsepp, K., Nardi, E.
Format: Preprint
Published: 2026
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author Gabrielli, E.
Lind, A.
Marzola, L.
Müürsepp, K.
Nardi, E.
author_facet Gabrielli, E.
Lind, A.
Marzola, L.
Müürsepp, K.
Nardi, E.
contents We propose a novel test of the unitarity of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix at collider experiments. Our approach exploits the incomplete cancellation between $t$-channel neutrino exchange and $s$-channel gauge-boson contributions that arises in the presence of violation of the flavor-diagonal PMNS unitarity conditions, leading to an anomalous growth of the cross section with energy. Such effects are generic in extensions of the Standard Model in which light neutrinos mix with heavier states, and can manifest at colliders as long as the characteristic energy of the process remains below the mass threshold of the new degrees of freedom. After briefly reviewing these scenarios, we employ our strategy to derive model-independent bounds on flavor diagonal unitarity-violating effects using LEP-II data. We then present sensitivity projections for future lepton and hadron colliders, demonstrating that they are well suited to probe the unitarity of the neutrino mixing matrix with this method.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12385
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Testing the unitarity of the light neutrino mixing matrix
Gabrielli, E.
Lind, A.
Marzola, L.
Müürsepp, K.
Nardi, E.
High Energy Physics - Phenomenology
High Energy Physics - Experiment
We propose a novel test of the unitarity of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix at collider experiments. Our approach exploits the incomplete cancellation between $t$-channel neutrino exchange and $s$-channel gauge-boson contributions that arises in the presence of violation of the flavor-diagonal PMNS unitarity conditions, leading to an anomalous growth of the cross section with energy. Such effects are generic in extensions of the Standard Model in which light neutrinos mix with heavier states, and can manifest at colliders as long as the characteristic energy of the process remains below the mass threshold of the new degrees of freedom. After briefly reviewing these scenarios, we employ our strategy to derive model-independent bounds on flavor diagonal unitarity-violating effects using LEP-II data. We then present sensitivity projections for future lepton and hadron colliders, demonstrating that they are well suited to probe the unitarity of the neutrino mixing matrix with this method.
title Testing the unitarity of the light neutrino mixing matrix
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2603.12385