Q value of the superallowed decay of 46V and its influence on Vud and the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. Academic Article uri icon


  • The masses of the radioactive nuclei (46)V and its decay daughter (46)Ti have been measured with the Canadian Penning Trap on-line Penning trap mass spectrometer to a precision of 1 x 10(-8). A Q(EC) value of 7052.90(40) keV for the superallowed beta decay of (46)V is obtained from the difference of these two masses. With this precise Q value, the Ft value for this decay is determined with improved precision. An investigation of an earlier Q-value measurement for (46)V uncovers a set of 7 measurements that cannot be reconciled with modern data and affects previous evaluations of V(ud) from superallowed Fermi decays. A new evaluation, adding our new data and removing the discredited subset, yields new values for G(V) and V(ud). When combined with recent results for V(us), this yields modified constraints for the unitarity of the Cabibbo-Kobayashi-Maskawa matrix and other extensions of the standard model.

published proceedings

  • Phys Rev Lett

author list (cited authors)

  • Savard, G., Buchinger, F., Clark, J. A., Crawford, J. E., Gulick, S., Hardy, J. C., ... Wang, Y.

citation count

  • 84

complete list of authors

  • Savard, G||Buchinger, F||Clark, JA||Crawford, JE||Gulick, S||Hardy, JC||Hecht, AA||Lee, JKP||Levand, AF||Scielzo, ND||Sharma, H||Sharma, KS||Tanihata, I||Villari, ACC||Wang, Y

publication date

  • September 2005