Abstract:
In this paper, we show the instability of a charged massive scalar field in bound states
around Kerr–Sen black holes. By matching the near and far region solutions of the radial
part in the corresponding Klein–Gordon equation, one can show that the frequency
of bound state scalar fields contains an imaginary component which gives rise to an
amplification factor for the fields. Hence, the unstable modes for a charged and massive
scalar perturbation in Kerr–Sen background can be shown.
