Covariant Vertex Operators for Cosmic Strings

TL;DR

This paper constructs covariant coherent state vertex operators in bosonic string theory, revealing their classical interpretation and potential applications to cosmic string evolution, with a focus on the lightlike compactification requirement.

Contribution

It introduces a new method to construct covariant coherent states in string theory, including the necessary lightlike compactification, and relates them to classical solutions and lightcone gauge states.

Findings

Covariant coherent states require lightlike compactification.

States share the same mass and angular momenta in different gauges.

Potential application to cosmic string evolution studies.

Abstract

We construct complete sets of (open and closed string) covariant coherent state and mass eigenstate vertex operators in bosonic string theory. By minimally extending the standard definition of coherent states so as to include the string theory requirements, we show that the naive construction of the the closed string coherent states requires the existence of a lightlike compactification of spacetime. When the null winding states in the underlying Hilbert space are projected out the resulting vertex operators satisfy the definition of a coherent state and have a classical interpretation. We present explicitly both the covariant and lightcone gauge realization of the resulting states using the DDF map that relates the two. We also identify the corresponding general lightcone gauge classical solutions around which the quantum states are fluctuating. We go on to show that both the covariant gauge coherent vertex operators, the corresponding lightcone gauge coherent states and the classical solutions all share the same mass and angular momenta and conjecture that the covariant and lightcone gauge states are different manifestations of the same state and share identical interactions. This construction can be used to study the evolution of fundamental cosmic strings as predicted by string theory and may also be useful for other applications where massive string vertex operators are of interest.