title: Spin correlations of strongly interacting massive fermion pairs as a test of Bell's inequality.
abstract: We report the results of the first-time test of the local hidden variable theories (Bell-Clauser-Horne-Shimony-Holt) involving strongly interacting pairs of massive spin 1/2 hadrons from the decay of short-lived (tau<10;-21sec) 2He spin-singlet state, populated in the nuclear reaction 2H+;1H-->;2He+n. The novel features of this experiment are (a) the use of an 'event-ready' [corrected] detector of nearly 100% efficiency to prepare an unbiased sample and (b) a focal-plane polarimeter of full 2pi sr acceptance with a random "post selection" of the reference axes. The spin-correlation function is deduced to be S[exp](pi/4)=2.83+/-0.24stat+/-0.07sys. This result is in agreement with nonlocal quantum mechanical prediction and it violates the Bell-CHSH inequality of |S|<or=2 at a confidence level of 99.3%.
authors.affiliation: Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan.
authors.forename: H
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authors.lastname: Sakai
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authors.lastname: Saito
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authors.lastname: Ikeda
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authors.lastname: Itoh
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authors.lastname: Kawabata
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authors.lastname: Kuboki
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authors.lastname: Maeda
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authors.lastname: Matsui
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authors.lastname: Rangacharyulu
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authors.lastname: Sasano
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authors.lastname: Satou
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authors.lastname: Sekiguchi
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authors.lastname: Suda
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authors.lastname: Tamii
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authors.lastname: Uesaka
authors.forename: K
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authors.lastname: Yako