Signatures of generalized ALP interactions in SM decays of mesons

TL;DR

This paper investigates how axion-like particles (ALPs) can indirectly influence standard meson decays, altering form factors and decay distributions, and derives bounds from experimental data to constrain ALP interactions.

Contribution

It introduces a generalized ALP Lagrangian framework to analyze indirect effects in meson decays and derives experimental bounds from NA48/2 data.

Findings

Bounds on ALP interactions from meson decay data

Modification of hadronic form factors due to ALPs

Potential deviations in meson mass spectra and decay sum rules

Abstract

In addition to giving rise to spectacular new physics signals in the final states of meson decays, Axion-like-particles also induce modifications in the standard model decays of mesons. These `indirect' signatures can be parametrized as the modifications of the hadronic form factors and can be probed using meson decay width and decay distribution measurements. Starting with a generalized ALP Lagrangian, we demonstrate these effects for semileptonic Kaon decays and derived bounds using NA48/2 data. We also briefly discuss other indirect signatures such as modification of meson mass spectrum and `sum rules' comprised of meson decay amplitudes which show deviation in presence of ALP.