TY - JOUR
T1 - Low-energy test of second-class current in β decays of spin-aligned 20F and 20Na
AU - Minamisono, K.
AU - Nagatomo, T.
AU - Matsuta, K.
AU - Levy, C. D.P.
AU - Tagishi, Y.
AU - Ogura, M.
AU - Yamaguchi, M.
AU - Ota, H.
AU - Behr, J. A.
AU - Jackson, K. P.
AU - Ozawa, A.
AU - Fukuda, M.
AU - Sumikama, T.
AU - Fujiwara, H.
AU - Iwakoshi, T.
AU - Matsumiya, R.
AU - Mihara, M.
AU - Chiba, A.
AU - Hashizume, Y.
AU - Yasuno, T.
AU - Minamisono, T.
PY - 2011/11/16
Y1 - 2011/11/16
N2 - 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.
AB - 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.
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U2 - 10.1103/PhysRevC.84.055501
DO - 10.1103/PhysRevC.84.055501
M3 - Article
AN - SCOPUS:82155184714
SN - 0556-2813
VL - 84
JO - Physical Review C - Nuclear Physics
JF - Physical Review C - Nuclear Physics
IS - 5
M1 - 055501
ER -