Dirac quasinormal modes in spherically symmetric regular black holes

Using the WKB approximation, massless and massive Dirac quasinormal modes (QNMs) are studied in spherically symmetric regular spacetimes. We analyze the relationships between QNM frequencies and the parameters (angular momentum number $l$, magnetic monopole charge $\ensuremath{\beta}$, and the mass of the field $m$) and discuss the extreme charge of magnetic monopole ${\ensuremath{\beta}}_{e}$ for spherically symmetric regular black holes. Furthermore, we apply an expansion method to expand QNMs in inverse powers of $L=l+1/2$ and confirm good precision with $l>n$. Finally, we improve the traditional finite difference method to be available in the massive Dirac case and illuminate the dynamical evolution of the massive Dirac field.