"Kaons: Precision Tests and Flavourful New-Physics Opportunities"

Kaon physics offers a relatively small set of observables, but some of the most sensitive probes of physics beyond the Standard Model, especially in scenarios with new sources of flavour and CP violation. Important examples include the rare decays K -> pivvbar, indirect CP violation through epsilon_K, and observables from the time dependent rates of K->mu^+mu^-. Precise Standard-Model and beyond-the-Standard-Model predictions are needed to identify small new-physics contributions, and I will discuss the current status of this precision frontier, with emphasis on recent developments for K -> pivvbar and related modes. Kaon experiments can also probe new physics beyond standard measurements of integrated decay rates: kinematic distributions can be sensitive to non-standard operator structures generated by heavy new physics, including signatures related to lepton number violation. Finally, rare kaon decays provide strong constraints and discovery opportunities for light new physics. I will illustrate this with the example of the QCD axion, for which kaon experiments are already probing parameter space relevant for axion dark matter.