New limit of the G-parity irregular induced tensor current and of the axial charge in the weak nucleon current detected in alignment correlation terms of 12B and 12N β decays

✍ Scribed by K. Minanisono; T. Yamaguchi; K. Matsuta; T. Minamisono; T. Ikeda; Y. Muramoto; M. Fukuda; Y. Nojiri; A. Kitagawa; K. Koshigiri; M. Morita

• Book ID: 104334133
• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 347 KB
• Volume: 654
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(00)88580-2

✦ Synopsis

The []-ray angular distributions from purely spin aligned t2B and J2N were precisely remeasured using a further refined spin-manipulation technique. We determined the amount of a G-parity violating induced tensor form factor in a weak axial vector current as 2MfT/f A = + 0.22 + 0.05(stat) + 0.15(syst) + 0.05(theor.). The result is consistent with the theoretical prediction in the framework of which induced tensor form factor is proportional to the u-and d-quark mass difference. We also determined the axial charge of the weak nucleon current to be y = 4.66 + 0.06(stat) + 0.13(syst), which can be explained mainly in terms of the impulse value YIA and soft pion exchange effect YEX" There, however, remains 18 % unexplained part of the experimental value relative to the theoretical value Yth = Y~A + YEX = 4.12. An in medium mass reduction of 12 + 4 % may explain the unexplained part if there is such an effect for the decaying nucleon.