# Closed Superstring Field Theory and its Applications

## TL;DR

This paper reviews recent advances in superstring field theory, focusing on heterotic and type II models, and discusses methods for quantum corrections, mass calculations, and unitarity proofs, highlighting divergence issues in different dimensions.

## Contribution

It introduces systematic procedures for quantum corrections, vacuum shifts, and unitarity proofs in superstring field theories, advancing the understanding of their mathematical consistency.

## Key findings

- S-matrix is divergence-free in more than 4 dimensions
- Infrared divergences occur in 4 or fewer dimensions
- Provides a framework for calculating quantum corrections in string theory

## Abstract

We review recent developments in the construction of heterotic and type II string field theories and their various applications. These include systematic procedures for determining the shifts in the vacuum expectation values of fields under quantum corrections, computing renormalized masses and S-matrix of the theory around the shifted vacuum and a proof of unitarity of the S-matrix. The S-matrix computed this way is free from all divergences when there are more than 4 non-compact space-time dimensions, but suffers from the usual infrared divergences when the number of non-compact space-time dimensions is 4 or less.