Circular strings, wormholes and minimum size

TL;DR

This paper quantizes circular strings in anti-de Sitter space, finds a discrete mass spectrum, and compares it with a scalar field cosmology, revealing a shared classical solution but different quantum spectra with a minimum size bound.

Contribution

It introduces a quantum analysis of circular strings in AdS space and compares their properties with cosmological models, highlighting differences in quantum spectra.

Findings

Discrete string mass spectrum in AdS space

Quantum equivalence and differences with scalar field cosmology

Minimum size bound for spacetime in both models

Abstract

The quantization of circular strings in an anti-de Sitter background spacetime is performed, obtaining a discrete spectrum for the string mass. A comparison with a four-dimensional homogeneous and isotropic spacetime coupled to a conformal scalar field shows that the string radius and the scale factor have the same classical solutions and that the quantum theories of these two models are formally equivalent. However, the physically relevant observables of these two systems have different spectra, although they are related to each other by a specific one-to-one transformation. We finally obtain a discrete spectrum for the spacetime size of both systems, which presents a nonvanishing lower bound.