$K^{\pm }\to \ddot{I}{€}^{\pm }a$ at Next-to-Leading Order in Chiral Perturbation Theory and Updated Bounds on ALP Couplings

Claudia Cornella, Anne Mareike Galda, Matthias Neubert +1

The weak decays $K^{\pm }\to \ddot{I}{€}^{\pm }a$ offer a powerful probe of axion-like particles (ALPs). In this work, we provide a comprehensive analysis of these processes within chiral perturb…