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 ${ \cal B}({ \pi}^{ 0}\to e^+ e^-)$ cannot be resolved when the constraints from $\Upsilon\to\gamma A_1^0$, $a_{ \mu}$ 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.
Categories: hep-ph