A global analysis of ALP-mediated multiboson production at the LHC

TL;DR

This paper conducts the first comprehensive global analysis of ALP-mediated multiboson production at the LHC, combining various measurements to constrain ALP couplings and explore EFT validity at multi-TeV scales.

Contribution

It introduces a novel global analysis framework for ALP-induced multiboson processes, integrating multiple final states and assessing EFT applicability at high energies.

Findings

Dijet channel provides the strongest sensitivity to ALP couplings.

Diboson and VBF processes offer complementary constraints.

Current data probes multi-TeV scales, with future datasets promising improved limits.

Abstract

Axion-like particles (ALPs) provide a well-motivated framework for physics beyond the Standard Model, coupling to gauge bosons through dimension-five operators protected by an approximate shift symmetry. At the LHC, such interactions lead to distinctive signatures in multiboson production, where the ALP appears as an off-shell mediator rather than a narrow resonance. In this work, we present the first global analysis of ALP-mediated multiboson processes, combining measurements of diphoton, ZZ, $W^+ W^-$, dijet, and vector-boson-fusion final states. On the theory side, motivated from a UV perspective, we assume that the ALP couples only to the gauge sector of the SM, and classify the ALP-multiboson vertices that directly govern collider observables. Our results show that the dijet channel dominates the sensitivity to ALP couplings and determines the limits on $c_{\tilde{G}}$, while diboson and VBF processes provide complementary constraints on the electroweak couplings. We further assess the validity of the EFT expansion given the multi-TeV scales probed in the data. This global study provides the most comprehensive picture to date of ALP-gauge interactions from multiboson production at the LHC, and highlights the opportunities for significant improvements with future high-luminosity datasets.