Dilaton Deformations in Closed String Field Theory

TL;DR

This paper investigates the structure of quartic interactions in closed string field theory, focusing on dilaton deformations, and provides evidence that the theory can handle large dilaton variations.

Contribution

It introduces a method to compute quartic interactions for complex states and analyzes how these interactions behave with increasing level, supporting the theory's robustness.

Findings

Quartic interactions become suppressed at higher levels.

Closed string field theory can describe large dilaton deformations.

The study refines rules for level expansion in string interactions.

Abstract

The dilaton theorem implies that the contribution to the dilaton potential from cubic interactions of all levels must be cancelled by the elementary quartic self-coupling of dilatons. We use this expectation to test the quartic structure of closed string field theory and to study the rules for level expansion. We explain how to use the results of Moeller to compute quartic interactions of states that, just like the dilaton, are neither primary nor have a simple ghost dependence. Our analysis of cancellations is made richer by discussing simultaneous dilaton and marginal deformations. We find evidence for two facts: as the level is increased quartic interactions become suppressed and closed string field theory may be able to describe arbitrarily large dilaton deformations.