Greybody Factor in AdS Black Brane Spectroscopy: A Study with Scalar and Electromagnetic Perturbations

We compute the greybody factor for scalar and photon radiations in AdS Schwarzschild black brane. We consider the linearized field equations satisfied by the minimally coupled massive scalar field and the transverse components of the Maxwell fields on the black brane background and recast them to the Heun's equations by appropriate change of variables and field redefinitions. At the asymptotic region, we consider appropriate linear combinations of the normalizable and non-normalizable solutions of the field equations to construct in/outgoing modes. We consider the ingoing solutions near horizon to construct the IN state and compute the coefficients of the in- and outgoing modes of the asymptotic solutions in terms of the connection coefficients of the Heun functions. Finally by calculating ratio of the coefficient of outgoing modes to the ingoing modes we find an exact expression for the greybody factor. We find that the greybody factor for the transverse Maxwell fields and that for the scalars dual to the conformal scalar primaries with odd integer scaling dimensions vanish off.