Information in Black Hole Radiation

TL;DR

If black hole formation evaporation can be described by an S matrix, information would be expected to come out in black hole radiation, but an estimate shows that it may come out initially so slowly, or else be so spread out, that it would never show up in an analysis perturbative in M/M.

Abstract

If black hole formation and evaporation can be described by an $S$ matrix, information would be expected to come out in black hole radiation. An estimate shows that it may come out initially so slowly, or else be so spread out, that it would never show up in an analysis perturbative in $M_{Planck}/M$, or in 1/N for two-dimensional dilatonic black holes with a large number $N$ of minimally coupled scalar fields.