Scalar field entanglement entropy of a Schwarzschild black hole from the Schmidt decomposition viewpoint

Scalar field entropy generated with the black hole horizon is considered in the light of the Schmidt decomposition to internal and external states of the field. Within the frame of this approach, the unitary character of the black hole evolution appears to be natural. We estimated the ratio of radiation field entropy to the Bekenstein-Hawking entropy, which has appeared to be small; in the zeroth order the ratio is constant. The obtained corrections to the massive radiation component are found to have both negative and positive values, hence witnessing the possibility of the information outflow from the black holes.