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Impact of the $a_{1} (1260) π$ cascade contribution on $D^{0} \to π^{+} π^{-} ℓ^{+} ℓ^{-}$ decays

Eleftheria Solomonidi ^1,2 and Luiz Vale Silva ³

¹PSI Center for Neutron and Muon Sciences, 5232 Villigen PSI, Switzerland
²Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
³Departamento de Matemáticas, Física y Ciencias Tecnológicas, Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Alfara del Patriarca, València, Spain

Phys. Rev. D 113, 094035 – Published 26 May, 2026

DOI: https://doi.org/10.1103/j39k-1jkq

Abstract

For the first time, we incorporate the cascade-type topology $D^{0} \to π^{-} a_{1}^{+} (1260) (\to π^{+} ρ^{0} (\to ℓ^{+} ℓ^{-}))$ to describe the recently measured rare charm-meson decays. We find that it comprises one of the largest contributions to the decay rate and obtain an unprecedented agreement of the Standard Model prediction with the available LHCb data while also aptly describing four-body nonleptonic transitions. In the presence of this cascade component, we predict that some angular observables acquire nonzero values, further stressing its phenomenological relevance and its potential for constraining new physics.

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References (44)

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Phys. Rev. D 113, 094035– Published 26 May, 2026

Vol. 113, Iss. 9 — 1 May 2026

Received 18 November 2025
Accepted 24 April 2026

DOI: https://doi.org/10.1103/j39k-1jkq

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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Impact of the $a_{1} (1260) π$ cascade contribution on $D^{0} \to π^{+} π^{-} ℓ^{+} ℓ^{-}$ decays

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Impact of the a1(1260)π cascade contribution on D0→π+π−ℓ+ℓ− decays

Abstract

Physics Subject Headings (PhySH)

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References (44)

Impact of the $a_{1} (1260) π$ cascade contribution on $D^{0} \to π^{+} π^{-} ℓ^{+} ℓ^{-}$ decays