Search For The Rare Decays K-L -> Pi(0)Pi(0)Mu(+)Mu(-) And K-L -> Pi(0)Pi X-0(0) -> Pi(0)Pi(0)Mu(+)Mu(-)

The KTeV E799 experiment has conducted a search for the rare decays, K-L -> pi(0)pi(0)mu(+)mu(-) and K-L -> pi(0)pi X-0(0) -> pi(0)pi(0)mu(+)mu(-), where the X-0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214: 3 +/- 0: 5) MeV/c(2). We find no evidence for either decay. We obtain upper limits of Br(K-L -> pi(0)pi(0)mu(+)mu(-) -> pi(0)pi X-0(0) -> pi(0)pi(0)mu(+)mu(-) ) < 1.0 x 10(-10) and Br(K-L -> pi(0)pi(0)mu(+)mu(-)) < 9.2 x 10(-11) at the 90% confidence level. This result rules out the pseudoscalar X-0 as an explanation of the HyperCP K-L result under the scenario that the (d) over bar sX(0) coupling is completely real.