Rare decay ${\pi }^0\to e^{+}{e}^{-}$ constraints on the light CP-odd Higgs in NMSSM

Abstract

We constrain the light CP-odd Higgs $A_1^0$ in NMSSM via the rare decay ${\pi }^0\to e^{+}{e}^{-}$. It is shown that the possible $3\sigma$ discrepancy between theoretical predictions and the recent KTeV measurement of $\mathcal{B}({\pi }^0\to e^{+}{e}^{-})$ cannot be resolved when the constraints from ${\rm Y}\to \gamma A_1^0$, $a_{\mu }$ and ${\pi }^0\to \gamma \gamma$ are combined. Furthermore, the combined constraints also exclude the scenario involving $m_{A_1^0}=214.3$ MeV, which is invoked to explain the anomaly in the ${\Sigma }^{+}\to p{\mu }^{+}{\mu }^{-}$ decay found by the HyperCP Collaboration.

Comments: 16 pages, 5 figures. Title changed, pi-A mixing included. Version to appear in PLB