Greybody factor of scalar field from Reissner-Nordstrom-de Sitter black   hole
  In this work we derive a general expression for the greybody factor of non-minimally coupled scalar fields in Reissner-Nordstr\"om-de Sitter spacetime in low frequency approximation. In particular case of zero momentum, greybody factor tends to zero in low frequency limit as frequency squared goes to zero for non-vanishing coupling. We also elaborate the significance of the results by giving formulae of differential energy rate and general absorption cross section. The greybody factor gives insight into the spectrum of Hawking radiations. 
Jamil Ahmed and K. Saifullah
gr-qc hep-th