A Note on Closed Strings

TL;DR

This paper investigates a special class of closed strings, revealing their classical and quantum behaviors resemble open strings, and discusses their spectrum, interactions with D branes, and effective actions.

Contribution

It introduces a specific type of closed strings that mimic open string properties at different levels and explores their spectrum and effective field theories.

Findings

Closed strings behave like two open strings classically.

At the quantum level, they behave as a single open string.

They contain a massless vector field in their spectrum.

Abstract

Special kind of closed strings is considered. It is shown that these closed strings behave as two (an even number of) open strings at the classical level and one open string at the quantum level. They contain massless vector field in their spectrum and can lie on D branes. Some properties of closed string field effective action are declared.