The Contribution of the Three-Body Process in the Nonmesonic Weak Decay of the _Λ¹²C Hypernucleus.

¹ Department of Physics and Astronomy, Seoul National University, Seoul, 151-747, Korea
² Department of Physics, Osaka University, Toyonaga 560-0043, Japan
³ High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
⁴ Gesellschaft fur Schwerionenforschung mbH (GSI), Darmstadt 64291 Germany
⁵ Lab. of Physics, Osaka Electro Communication University, Neyagawa 572-8530, Japan
⁶ Department of Physics, Tohoku University, Sendai 980-8578, Japan
⁷ Department of Physics, Ewha Womans University, Seoul 120-750, Korea
⁸ Korea Research Institute of Standards and Science (KRISS), Daejeon 305-600, Korea
⁹ Department of Physics, University of Tokyo, Hongo 113-0033, Japan
¹⁰ Department of Physics, Tokyo Institute of Technology, Ookayama 152-8551, Japan
¹¹ Riken Nishina Center, Riken, Wako 351-0198, Japan
¹² Department of Physics, Kyoto University, Kyoto 606-8502, Japan
¹³ Japan Atomic Energy Research Institute, Tokai 319-1195, Japan

^a e-mail: bhang@snu.ac.kr

Abstract

The serious inconsistency problem between the values of experimental and theoretical Γ_n /Γ_p ratio of the nonmesonic weak decay of Λ hypernuclei has been resolved recently. We have shown that the reason behind the problem was the quenching of the nucleon yields which in turn was due to the contribution of the three-body process. We have measured that the branching ratio of the three-body process in nonmesonic weak decay, 0.29±0.13, is so large that the absolute values of Γ_n and Γ_p must be determined taking account of the contribution of the 3-body process. In this paper, the recent studies toward the finding of the 3-body process via the exclusive coincidence experiments are presented.