{"paper":{"title":"Search for a light pseudoscalar particle in the decay $K^0_L \\to \\pi^0 \\pi^0 X$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"A. Lednev, A. Moisseenko, A. S. Kurilin, A. Sugiyama, E. Iwai, E. Kuzmin, G. N. Perdue, G. Y. Lim, H. Ishii, H. Morii, H. Nanjo, H. Okuno, H. Sato, H. S. Lee, H. Watanabe, H. Y. Yoshida, I. Kato, J. Comfort, J. K. Ahn, J. Ma, J. Nix, K. F. Chen, K. Omata, K. Sakashita, M. Doroshenko, M. L. Wu, M. Nomachi, M. Sekimoto, M. Yamaga, N. Ishihara, N. Sasao, R. Ogata, S. Ishibashi, S. Kobayashi, S. Podolsky, S. Suzuki, S. Takita, S. Y. Lee, T. Inagaki, T. Iwata, T. K. Komatsubara, T. Matsumura, T. Morimoto, T. Nakano, T. Nomura, T. Sasaki, T. Sato, T. Shinkawa, T. Sumida, T. Tsukamoto, T. Yamanaka, V. Baranov, Y. Akune, Y. B. Hsiung, Y. C. Tung, Y. Fujioka, Y. Sugaya, Y. Tajima, Y. Wah, Y. Yoshimura, Y. Zheng, Z. Tsamalaidze","submitted_at":"2008-10-23T10:11:32Z","abstract_excerpt":"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/$c^2$ was suggested by the HyperCP experiment. We found no evidence for $X$ and set an upper limit on the product branching ratio for $K_L^0->pi0pi0X$, $X->\\gamma\\gamma$ of $2.4 \\times 10^{-7}$ 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."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0810.4222","kind":"arxiv","version":3},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/0810.4222/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}