Shell model study of first-forbidden beta decay around ²⁰⁸Pb

In the present work, we report a systematic theoretical study of the log ft values for the forbidden beta(-) decay transitions in the Pb-208 region. For this, we have considered Hg-206 -> Tl-206, Hg-208 -> Tl-208, Tl-206 -> Pb-206 and Tl-208 -> Pb-208 transitions. We have performed shell model calculations using KHH7B interaction in valence shell 58-114 for protons and 100-164 for neutrons by considering 1p - 1h excitations for both protons and neutrons simultaneously for daughter nuclei. This study presents the first shell model results of beta(-)-decay corresponding to the recent experimental data.