%0 Journal Article
%A Bertuzzo, Enrico
%A Grojean, Christophe
%A Salla, Gabriel M.
%T ALPs, the on-shell way
%J Journal of high energy physics
%V 2024
%N 5
%@ 1029-8479
%C [Trieste]
%I SISSA
%M PUBDB-2024-05521
%M arXiv:2311.16253
%M CERN-TH-2023-202
%M DESY-23-090
%M HU-EP-23/21
%P 175
%D 2024
%Z 32 pages + appendices; v2: minor modifications, matches version published in JHEP
%X We study how the coupling between axion-like particles (ALPs) and matter can be obtained at the level of on-shell scattering amplitudes. We identify three conditions that allow us to compute amplitudes that correspond to shift-symmetric Lagrangians, at the level of operators with dimension 5 or higher, and we discuss how they relate and extend the Adler's zero condition. These conditions are necessary to reduce the number of coefficients consistent with the little-group scaling to the one expected from the Lagrangian approach. We also show how our formalism easily explains that the dimension-5 interaction involving one ALP and two massless spin-1 bosons receive corrections from higher order operators only when the ALP has a non-vanishing mass. As a direct application of our results, we perform a phenomenological study of the inelastic scattering <i>l</i><sup>+</sup><i>l</i><sup>−</sup> → ϕh (with <i>l</i><sup>±</sup> two charged leptons, ϕ the ALP and h the Higgs boson) for which, as a result of the structure of the 3-point and 4-point amplitudes, dimension-7 operators can dominate over the dimension-5 ones well before the energy reaches the cutoff of the theory.
%K dimension: 5 (INSPIRE)
%K operator: higher-order (INSPIRE)
%K scattering amplitude: on-shell (INSPIRE)
%K lepton (INSPIRE)
%K axion: mass (INSPIRE)
%K axion-like particles (INSPIRE)
%K inelastic scattering (INSPIRE)
%K scaling (INSPIRE)
%K Higgs particle (INSPIRE)
%K structure (INSPIRE)
%K Axions and ALPs (autogen)
%K New Light Particles (autogen)
%K Specific BSM Phenomenology (autogen)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:001227189800001
%R 10.1007/JHEP05(2024)175
%U https://bib-pubdb1.desy.de/record/613032