Recent progresses in the study of nonmesonic weak decay of Λ hypernuclei

H. Bhang, S. Ajimura, K. Aoki, A. Banu, T. Fukuda, O. Hashimoto, J. I. Hwang, S. Kameoka, B. H. Kang, E. Kim, J. H. Kim, M. Kim, T. Maruta, Y. Miura, Y. Miyake, T. Nagae, M. Nakamura, S. N. Nakamura, H. Noumi, S. OkadaY. Okayasu, H. Outa, H. Park, P. K. Saha, Y. Sato, M. Sekimoto, S. Shin, T. Takahashi, H. Tamura, K. Tanida, A. Toyota, K. Tsukata, T. Watanabe, H. J. Yim

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Fundamental interest on Non Mesonic Weak Decay (NMWD) is that it provides practically the only means to study the elementary δS = 1 baryonbaryon weak interaction process, ΛN→NN (Λp → np and Λn → nn), since it is difficult to be realized in the free space. Thanks to the recent developments in experimental and theoretical studies, the relative strength of two channels, the Γnp ratios whose experimental and theoretical values have showed a long standing discrepancy have been converged to ∼0.5 and the discrepancy problem finally has been solved.1-3 However, despite the progresses, the decay interaction of NMWD is not yet well established and there remain the important issues such as the discrepancy of asymmetry parameter between experimental and theoretical values, confirmation of 3-body NMWD process, and whether the I = 1/2 rule for δS = 1 decay would hold or not in NMWD. Especially the recent experimental indication of the 3-body decay process ΛNN → NNN whose contribution was predicted to be significant in the theoretical calculations seems to be strong and showed a surprisingly large contribution in the quenching of singles and coincidence nucleon yields in NMWD. Recent results of the asymmetry parameter αnm of NMWD showed small values for both s-shell 5Λ He and p-shell 12 Λ C and consistent with each other. However, the discrepancy of the theoretical values from those of experimental ones remains to be understood. It now becomes one of the urgent issues in NMWD study to determine the contribution of the 3-body NMWD channel experimentally, in order to understand the discrepancy of the asymmetry papameter, and to test the δI = 1/2 rule for NMWD which are the main purposes of J-PARC 50 GeV PS experiment, E18 and E22.

Original languageEnglish
Title of host publicationProceedings of the Sendai International Symposium
Subtitle of host publicationStrangeness in Nuclear and Hadronic Systems, SENDAI 2008
Number of pages8
Publication statusPublished - 2010
EventSendai International Symposium on Strangeness in Nuclear and Hadronic Systems, SENDAI 2008 - Sendai, Japan
Duration: 2008 Dec 142008 Dec 18

Publication series

NameProceedings of the Sendai International Symposium: Strangeness in Nuclear and Hadronic Systems, SENDAI 2008


OtherSendai International Symposium on Strangeness in Nuclear and Hadronic Systems, SENDAI 2008


  • Asymmetry parameter
  • Hypernuclei
  • NMWD
  • Three-body process

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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