0000000000385215
AUTHOR
N. Soukouti
Spin-dipole nuclear matrix elements for double beta decays and astro-neutrinos
Spin-dipole (SD) nuclear matrix elements (NMEs) M±(SD2) for unique first forbidden β±2−→0+ ground-state-to-ground-state transitions are studied by using effective microscopic two-nucleon interactions in realistic single-particle model spaces. The observed values of the NMEs Mexp±(SD2) are compared with the values of the single-quasiparticle NMEs Mqp±(SD2) without nucleon spin–isospin (στ) correlation and the QRPA NMEs MQRPA±(SD2) with the στ correlation. The observed SD matrix elements are found to be reduced by the factor k≈0.2 with respect to Mqp±(SD2) and by the factor kNM≈0.5 with respect to MQRPA±(SD2). We then infer that the SD NME is reduced considerably partly by the nucleon στ corr…
QEC value of the superallowed β emitter 42Sc
The QEC value of the superallowed β+ emitter Sc42 has been measured with the JYFLTRAP Penning-trap mass spectrometer at the University of Jyväskylä to be 6426.350(53) keV. This result is at least a factor of four more precise than all previous measurements, which were also inconsistent with one another. As a byproduct we determine the excitation energy of the 7+ isomeric state in Sc42 to be 616.762(46) keV, which deviates by 8σ from the previous measurement. peerReviewed
QEC value of the superallowed β emitter Sc42
Precise measurements of superallowed ${0}^{+}\ensuremath{\rightarrow}{0}^{+}$ $\ensuremath{\beta}$ decay presently provide the most precise value for the weak mixing amplitude ${V}_{u\phantom{\rule{0}{0ex}}d}$. As the largest element of the CKM matrix, ${V}_{u\phantom{\rule{0}{0ex}}d}$ is a critical piece of the Standard Model of the electroweak interaction. The new, precise Penning-trap mass measurement of the decay energy for the superallowed transition in ${}^{42}$Sc opens the door for a much more precise $f\phantom{\rule{0}{0ex}}t$ value determination if its half-life can be measured more precisely as well.