This presentation reports on the first experimental search for the decay Klong to $pi^0 pi^0 mu^+ mu^-$ based on data collected by the KTeV experiment. Although this decay mode is possible within the standard model, its rate is phase space suppressed
. The HyperCP experiment has recently observed 3 $Sigma^+ to p mu^+ mu^-$ events within a narrow di-muon mass range, suggesting that the process may occur via a new neutral state: $Sigma^+ to p X^0, X^0 tomu^+ mu^-$ with $m(X^0) = 214.3mev$. The $X^0$ would create an $s$- to $d$- quark transition at a rate that would cause Klong to $pi^0 pi^0 X, ^0 tomu^+ mu^-$ to occur at rates considerably over the standard model expectation. Our preliminary results significantly constrain this possibility.
