$K_L \to \pi^o \nu \bar{\nu}$ in the Aspon Model

Abstract

An attractive alternative to the standard model of CP violation is the aspon model. In this model, CP is spontaneously broken, automatically solving the strong CP problem. Recently, it has been shown that CP violation in the B system is much smaller in the aspon model than in the standard model. Here we provide a complementary study by considering $K_L\to \pi^o\nu\bar{\nu}$, which is almost entirely CP violating and free of hadronic uncertainties, and show that the rate in the aspon model is many orders of magnitude below the standard model rate. Observation of $K_L\to \pi^o\nu\bar{\nu}$ would rule out the aspon model.