H-Branes and Chiral Strings

TL;DR

This paper introduces H-branes, a new class of D-branes with a null direction, which can model quantum horizons like black holes and cosmological horizons through a modified boundary term in the string action.

Contribution

It constructs H-branes by adding a boundary term to the Polyakov action, leading to a novel description of horizons as boundary states in string theory.

Findings

H-branes describe quantum horizons such as black holes and de-Sitter spaces.

Open strings attached to H-branes map to chiral closed strings via Wick rotation.

Boundary states become squeezed states, indicating space/phase space transmutation.

Abstract

We add a simple boundary term to the Polyakov action and construct a new class of D-branes with a single null direction. On the string world-sheet the system is described by a single quantized left-mode sector of a conformal field theory. By a Wick rotation of spacetime, we map open strings attached to these branes into chiral closed strings. We suggest that these so-called H-branes describe quantum horizons - black hole, cosmological (de-Sitter), etc. We show how one can get a space/phase space transmutation near the horizon and discuss the new features of boundary states which become squeezed states.