Low-energy test of second-class current in β decays of spin-aligned 20F and 20Na

K. Minamisono, T. Nagatomo, K. Matsuta, C. D.P. Levy, Y. Tagishi, M. Ogura, M. Yamaguchi, H. Ota, J. A. Behr, K. P. Jackson, A. Ozawa, M. Fukuda, T. Sumikama, H. Fujiwara, T. Iwakoshi, R. Matsumiya, M. Mihara, A. Chiba, Y. Hashizume, T. YasunoT. Minamisono

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14 Citations (Scopus)


The G-parity-violating, second-class current- (SCC) induced tensor term in the weak-nucleon axial-vector current was determined from β-decay correlation measurements of the mass A = 20 mirror pair. The alignment correlation terms in the β-decay angular distribution from the purely spin aligned mirror pair, 20F and 20Na, were measured in the present study. Combining the present results with existing results of β and delayed γ-ray angular correlation measurements for the A = 20 mirror pair, the SCC-induced tensor term was extracted to be dII/Ac = 0.18 ± 0.48. In the extraction, the weak-magnetism term, b/Ac = 8.58 ± 0.28, evaluated from the M1 analog γ-ray decay strength, was used in a framework of the conserved vector current hypothesis. This is the first unambiguous extraction of the (b-dII)/Ac term free from the contribution of the second-forbidden form factor, j2, in the axial-vector current, which was a limiting factor for accurate determination of nonexistence of the SSC in the β decay of the A = 20 system.

Original languageEnglish
Article number055501
JournalPhysical Review C - Nuclear Physics
Issue number5
Publication statusPublished - 2011 Nov 16
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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