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arXiv · 2510.13953

Positivity and partial wave unitarity bounds on ALP theories via amplitude methods

Luigi C. Bresciani·Gabriele Levati·Paride Paradisi
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Abstract

We derive the complete set of partial wave unitarity bounds on the most general Axion-Like Particle (ALP) effective interactions up to dimension 8 in the limit of large center-of-mass energy. Exploiting a recently developed formalism based on spinor-helicity techniques, we discuss the unitarity bounds for $N \to M$ (with $N, M \geq 2$) scattering amplitudes that can be relevant for ALP searches at colliders or in a variety of rare processes. Moreover, we compute positivity bounds on ALP interactions, emphasizing their complementarity with partial wave unitarity bounds. As a byproduct, we show that our results can be used to infer new positivity constraints in the Standard Model Effective Field Theory.

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Luigi C. Bresciani, Gabriele Levati, Paride Paradisi. 2025-10-15. Positivity and partial wave unitarity bounds on ALP theories via amplitude methods. https://doi.org/10.1007/jhep07(2026)172

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