PRAMANA-JOURNAL OF PHYSICS, vol.74, no.4, pp.541-553, 2010 (SCI-Expanded)
The 0(+) a dagger" 0(-) first-forbidden beta decay transitions have been investigated for some spherical nuclei. The theoretical framework is based on a proton-neutron quasiparticle random phase approximation (pnQRPA). The Woods-Saxon potential basis has been used in our calculations. The transition probabilities have been calculated within the xi approximation. The relativistic beta moment matrix element has been calculated both directly without any assumption and assuming that it is proportional to the non-relativistic one.