Abouzaid, E.E.AbouzaidYEE HSIUNG et al2018-09-102018-09-102011-05http://inspirehep.net/record/901060http://scholars.lib.ntu.edu.tw/handle/123456789/364408Search for the Rare Decays $K_L \\to \\pi^0\\pi^0\\mu^+\\mu^-$ and $K_L \\to \\pi^0\\pi^0 X^0\\to \\pi^0\\pi^0\\mu^+\\mu^-$journal article10.1103/PhysRevLett.107.201803