Electroweak transitions in intermediate mass nuclei

We present beta decay rates and B(E2) strengths calculated using the \emph{ab initio} symmetry-adapted no-core shell model (SA-NCSM). The SA-NCSM utilizes emergent symmetries in nuclei in order to reduce the dimensionality of the model space. This, in turn, allows one to reproduce the low-energy nuclear dynamics with only a small fraction of the model space, and hence making solutions to heavier nuclei feasible. The symmetry-adapted basis of the SA-NCSM is well suited for describing electromagnetic and beta-decay transitions enabling us to use the full capability of the model and perform calculations for \emph{sd}-shell as well as \emph{pf}-shell nuclei. This work discusses the reproduction of B(E2) strengths in intermediate-mass nuclei from first principles and without effective charges. It also focuses on a study of the $g_A$ quenching problem for bare interactions (no renormalization involved) and with collective correlations that are well described within the model, as well as on a study of $^{48}$Ca and $^{48}$Ti of interest to neutrinoless double beta decays.