Dirac equation on the Kerr-Newman spacetime and Heun functions (Q2031625)

Summary: By employing a pseudoorthonormal coordinate-free approach, the Dirac equation for particles in the Kerr-Newman spacetime is separated into its radial and angular parts. In the massless case to which a special attention is given, the general Heun-type equations turn into their confluent form. We show how one recovers some results previously obtained in literature, by other means.