Search For A Light Pseudoscalar Particle In The Decay Kl0 -> Pi(0)Pi X-0

We performed a search for a light pseudoscalar particle X in the decay K-L(0) -> pi(0)pi X-0, X -> gamma gamma with the E391a detector at KEK. Such a particle with a mass of 214.3 MeV/c(2) was suggested by the HyperCP experiment. We found no evidence for X and set an upper limit on the product branching ratio for K-L(0) -> pi(0)pi X-0, X -> gamma gamma of 2.4 x 10(-7) at the 90% confidence level. Upper limits on the branching ratios in the mass region of X from 194.3 to 219.3 MeV/c(2) are also presented.