Two-phonon structures for beta-decay theory

The $\beta$-decay rates of ${}^{60}$Ca have been studied within a microscopic model, which is based on the Skyrme interaction T45 to construct single-particle and phonon spaces. We observe a redistribution of the Gamow-Teller strength due to the phonon-phonon coupling, considered in the model. For ${}^{60}$Sc, the spin-parity of the ground state is found to be $1^{+}$. We predict that the half-life of ${}^{60}$Ca is 0.3 ms, while the total probability of the $\beta xn$ emission is 6.1%. Additionally, the random matrix theory has been applied to analyse the statistical properties of the $1^{+}$ spectrum populated in the $\beta$-decay to elucidate the obtained results.