Strings, Virasoro Sandwiches and Worldsheet Horizons

TL;DR

This paper explores the quantization of free bosonic closed strings, revealing new classes of physical states influenced by worldsheet symmetries, and applies this to strings in accelerated frames and black hole horizons.

Contribution

It introduces a novel classification of string states based on worldsheet symmetries and develops a worldsheet thermal string theory framework.

Findings

Four classes of physical states identified based on parity and time reversal.

New classes of states break one or both symmetries, unlike traditional highest weight states.

Application to strings in accelerated frames and black hole horizons.

Abstract

We revisit the canonical quantization of free bosonic closed string theory and observe that the physicality of states requires vanishing of the worldsheet Virasoro algebra generators sandwiched between any two physical states. This requirement yields four classes of physical states, depending on discrete worldsheet symmetries: parity and time reversal. The usual string states which are highest weight states of the Virasoro algebra, preserve both, while the other new three classes break one or both. We apply our formulation to an accelerated worldsheet with horizons, initiating the worldsheet formulation of a thermal string theory and strings probing horizon of black holes.