Global phase time and path integral for string cosmological models

TL;DR

This paper identifies a global phase time in string cosmological models and derives the quantum transition amplitude using path integrals when an intrinsic time exists, advancing the understanding of quantum cosmology in string theory.

Contribution

It introduces a method to define a global phase time in string cosmological models and computes the quantum transition amplitude via path integrals.

Findings

Successful identification of a global phase time in string cosmology models

Derivation of quantum transition amplitudes using path integrals

Applicable when the Hamiltonian constraint admits intrinsic time

Abstract

A global phase time is identified for homogeneous and isotropic cosmological models yielding from the low energy effective action of closed bosonic string theory. When the Hamiltonian constraint allows for the existence of an intrinsic time, the quantum transition amplitude is obtained by means of the usual path integral procedure for gauge systems.