  If the HyperCP three events for the decay of $\Sigma^+\to p\mu^+\mu^-$ are
explained by a new pseudoscalar (axial-vector) boson $X_{P(A)}$ with a mass of
214.3 MeV, we study the constraints on the couplings between $X_{P(A)}$ and
fermions from the experimental data in $K$ and $B$ processes. Some implications
of the new particle on flavor changing $B$ and $\tau$ decays are given.
Explicitly, we show that the decay branching ratios of $B_{s}\to\phi
X_{P(A)}\to \phi\mu^{+}\mu^{-}$, $B_{d}\to K_{0}^{*}(1430){P(A)}\to
K_{0}^{*}(1430)\mu^{+}\mu^{-}$ and $\tau\to\mu X_{P(A)}\to\mu\mu^{+}\mu^{-}$
can be as large as $2.7 (2.8)\times 10^{-6}$, $7.4 (7.5)\times 10^{-7}$ and
$1.7 (0.14)\times 10^{-7}$, respectively.
