The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process

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

doi:10.1140/epja/i2007-10470-x

The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process

H. Bhang, S. Ajimura, K. Aoki, A. Banu, T. Fukuda, O. Hashimoto, J. I. Hwang, S. Kameoka, B. H. Kang, E. H. 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. Tsukada, T. Watanabe, H. J. Yim

School of Earth System Sciences

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Abstract

Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton- induced NMWD, Γ_n/Γ_p , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and ¹² _Λ C , respectively. These observations agree well with the improved theoretical Γ_n/Γ_p ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γ_n/Γ_p has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γ_n/Γ_p ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNN → nNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of ¹² _Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γ_n/Γ_p ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.

Original language	English
Pages (from-to)	259-263
Number of pages	5
Journal	European Physical Journal A
Volume	33
Issue number	3
DOIs	https://doi.org/10.1140/epja/i2007-10470-x
State	Published - Sep 2007

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Bhang, H., Ajimura, S., Aoki, K., Banu, A., Fukuda, T., Hashimoto, O., Hwang, J. I., Kameoka, S., Kang, B. H., Kim, E. H., Kim, J. H., Kim, M., Maruta, T., Miura, Y., Miyake, Y., Nagae, T., Nakamura, M., Nakamura, S. N., Noumi, H., ... Yim, H. J. (2007). The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process. European Physical Journal A, 33(3), 259-263. https://doi.org/10.1140/epja/i2007-10470-x

@article{4fea6a35919742fb982693ae2914406e,

title = "The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process",

abstract = "Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton- induced NMWD, Γn/Γp , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and 12 Λ C , respectively. These observations agree well with the improved theoretical Γn/Γp ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γn/Γp has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γn/Γp ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNN → nNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of 12 Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γn/Γp ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.",

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

year = "2007",

month = sep,

doi = "10.1140/epja/i2007-10470-x",

language = "English",

volume = "33",

pages = "259--263",

journal = "European Physical Journal A",

issn = "1434-6001",

publisher = "Springer",

number = "3",

}

Bhang, H, Ajimura, S, Aoki, K, Banu, A, Fukuda, T, Hashimoto, O, Hwang, JI, Kameoka, S, Kang, BH, Kim, EH, Kim, JH, Kim, M, Maruta, T, Miura, Y, Miyake, Y, Nagae, T, Nakamura, M, Nakamura, SN, Noumi, H, Okada, S, Okayasu, Y, Outa, H, Park, H, Saha, PK, Sato, Y, Sekimoto, M, Shin, S, Takahashi, T, Tamura, H, Tanida, K, Toyota, A, Tsukada, K, Watanabe, T & Yim, HJ 2007, 'The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process', European Physical Journal A, vol. 33, no. 3, pp. 259-263. https://doi.org/10.1140/epja/i2007-10470-x

TY - JOUR

T1 - The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process

AU - Bhang, H.

AU - Ajimura, S.

AU - Aoki, K.

AU - Banu, A.

AU - Fukuda, T.

AU - Hashimoto, O.

AU - Hwang, J. I.

AU - Kameoka, S.

AU - Kang, B. H.

AU - Kim, E. H.

AU - Kim, J. H.

AU - Kim, M.

AU - Maruta, T.

AU - Miura, Y.

AU - Miyake, Y.

AU - Nagae, T.

AU - Nakamura, M.

AU - Nakamura, S. N.

AU - Noumi, H.

AU - Okada, S.

AU - Okayasu, Y.

AU - Outa, H.

AU - Park, H.

AU - Saha, P. K.

AU - Sato, Y.

AU - Sekimoto, M.

AU - Shin, S.

AU - Takahashi, T.

AU - Tamura, H.

AU - Tanida, K.

AU - Toyota, A.

AU - Tsukada, K.

AU - Watanabe, T.

AU - Yim, H. J.

PY - 2007/9

Y1 - 2007/9

N2 - Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton- induced NMWD, Γn/Γp , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and 12 Λ C , respectively. These observations agree well with the improved theoretical Γn/Γp ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γn/Γp has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γn/Γp ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNN → nNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of 12 Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γn/Γp ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.

AB - Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton- induced NMWD, Γn/Γp , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and 12 Λ C , respectively. These observations agree well with the improved theoretical Γn/Γp ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γn/Γp has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γn/Γp ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNN → nNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of 12 Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γn/Γp ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.

UR - http://www.scopus.com/inward/record.url?scp=34548593969&partnerID=8YFLogxK

U2 - 10.1140/epja/i2007-10470-x

DO - 10.1140/epja/i2007-10470-x

M3 - Article

AN - SCOPUS:34548593969

SN - 1434-6001

VL - 33

SP - 259

EP - 263

JO - European Physical Journal A

JF - European Physical Journal A

IS - 3

ER -

The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process

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