White Holes, Black Holes and Cpt in Two Dimensions

TL;DR

The paper proposes a superscattering matrix in two-dimensional dilaton gravity that violates unitarity but preserves CPT symmetry when including certain Planck-scale excitations, highlighting challenges in low-energy effective theories.

Contribution

It introduces a novel superscattering matrix framework incorporating white hole states in two-dimensional gravity, addressing CPT invariance and unitarity issues at leading order in large-N expansion.

Findings

Existence of a unitarity-violating superscattering matrix with white hole states

Rules for computing superscattering in multiply-connected spacetimes

Discussion of potential issues beyond leading order in 1/N

Abstract

It is argued that a unitarity-violating but weakly CPT invariant superscattering matrix exists for leading-order large-$N$ dilaton gravity, if and only if one includes in the Hilbert space planckian ``thunderpop" excitations which create white holes. CPT apparently cannot be realized in a low-energy effective theory in which such states have been integrated out. Rules for computing the leading-large-$N$ superscattering are described in terms of quantum field theory on a single multiply-connected spacetime obtained by sewing the future (past) horizons of the original spacetime with the past (future) horizons of its CPT conjugate. Some difficulties which may arise in going beyond leading order in $1/N$ are briefly discussed.