Constraints on the new particle in ${\mathrm{\Sigma }}^{+}\to p{\mu }^{+}{\mu }^{-}$

The HyperCP collaboration has presented the branching ratio of $\Sigma^+\to p\mu^+\mu^-$tobe$(8.6^{+6.6}_{-5.4}\pm 5.5)\times 10^{-8}$ and suggested a new boson $P^0$ with a mass of $214.3\pm 0.5$ MeV to induce the flavor changing transition of $s\to d{\mu }^{+}{\mu }^{-}$. We demonstrate that to explain the data, the new particle cannot be a scalar but pseudoscalar based on the direct constraints from $K^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$ and $K_L\to {\mu }^{+}{\mu }^{-}$, respectively. Moreover, we determine that the decay width of the pseudoscalar should be in the range of ${10}^{-7}$ MeV with the lifetime of ${10}^{-14}$ sec.