Light Scalars and the Koto Anomaly

Abstract

We show that the recent excess presented by KOTO in their search for KL→π0νν may be due to weakly coupled scalars produced from Kaon decays. We study two concrete realizations, the minimal Higgs portal and a hadrophilic scalar model, and demonstrate that they can explain the observed events while satisfying existing limits. The simplicity of these models, and their possible relations to interesting UV constructions, provides strong theoretical motivation for a new physics interpretation of the KOTO data.