  In this paper, we study the collapse of a massive shell in 2+1 and 3+1
dimensional gravity with Anti-de Sitter asymptotics. Using the Gauss-Codazzi
method, we derive gravitational equations of motion of the shell. We then use
the functional Schrodinger formalism to calculate the spectrum of particles
produced during the collapse. At the late time, radiation agrees very well with
the standard Hawking results. In 3+1 dimensions, we reproduce the Hawking-Page
transition. We then construct the density matrix of this collapsing system and
analyze the information content in the emitted radiation. We find that the
off-diagonal elements of the density matrix are very important in preserving
the unitarity of the system.

High Energy Physics - Theory