Search for a light pseudoscalar particle in the decay $K_L^0\to {\pi }^0{\pi }^{0}X$

Y. C. Tung, Y. B. Hsiung, M. L. Wu +59

We performed a search for a light pseudoscalar particle $X$ in the decay $K_L^0->pi0pi0X$, $X->\gamma \gamma$ with the E391a detector at KEK. Such a particle with a mass of 214.3 MeV/$c^2$ wa…