Quasinormal modes of Rarita-Schwinger field in Reissner-Nordström black hole spacetimes

The Newman-Penrose formalism is used to deal with the quasinormal modes (QNMs) of Rarita-Schwinger perturbations outside a Reissner-Nordström black hole. We obtain four kinds of possible expressions of effective potentials, which are proved to be of the same spectra of quasinormal mode frequencies. The quasinormal mode frequencies evaluated by the WKB potential approximation show that, similar to those for Dirac perturbations, the real parts of the frequencies increase with the charge Q and decrease with the mode number n, while the dampings almost keep unchanged as the charge increases.