Exclusive proton asymmetry measurement in non-mesonic weak decay of polarized 5_Lambda_He

T. Maruta; S. Ajimura; K. Aoki; A. Banu; H. Bhang; T. Fukuda; O. Hashimoto; J. I. Hwang; S. Kameoka; B. H. Kang; E. H. Kim; J. H. Kim; M. J. Kim; 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; T. Takahashi; H. Tamura; K. Tanida; A. Toyoda; K. Tsukada; T. Watanabe; H. J. Yim

arXiv · nucl-ex/0509016

Exclusive proton asymmetry measurement in non-mesonic weak decay of polarized 5_Lambda_He

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Abstract

The asymmetry parameter alpha_p^NM for a proton exclusively emitted in the Lambda p -> np process was, for the first time, measured in the non-mesonic weak decay of a polarized 5_La,bda_He hypernucleus by selecting the proton-neutron pairs emitted in the back-to-back kinematics. The highly polarized 5_Lambda_He was abundantly produced with the (pi+,K+) reaction at 1.05GeV/c in the scattering angular range of +-15$ degrees. The obtained value alpha_p^NM=0.31+-0.22, as well as that for inclusive protons, alpha_p^NM=0.11+-0.08+-0.04, largely contradicts recent theoretical values of around -0.6, although these calculations well reproduce the branching ratios of non-mesonic weak decay.

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T. Maruta, S. Ajimura, K. Aoki, A. Banu, H. Bhang, T. Fukuda, O. Hashimoto, J. I. Hwang, S. Kameoka, B. H. Kang, E. H. Kim, J. H. Kim, M. J. Kim, 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, T. Takahashi, H. Tamura, K. Tanida, A. Toyoda, K. Tsukada, T. Watanabe, H. J. Yim. 2005-09-13. Exclusive proton asymmetry measurement in non-mesonic weak decay of polarized 5_Lambda_He. https://arxiv.org/abs/nucl-ex/0509016

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