Tachyon Condensation: Calculations in String Field Theory

TL;DR

This thesis investigates tachyon condensation in string field theories by calculating potentials in different models, verifying Sen's conjecture with high precision, and exploring exact solutions in toy models.

Contribution

It provides new calculations of the tachyon potential in both bosonic and superstring field theories, including an unpublished high-precision verification of Sen's conjecture.

Findings

Calculated tachyon potential in Witten's bosonic string field theory.

Calculated tachyon potential in Berkovits' superstring field theory.

Verified Sen's conjecture up to 94.4% in a toy model.

Abstract

In this Ph.D. thesis, we study tachyon condensation in string field theories. In chapter 2, we review Witten's bosonic string field theory and calculate the tachyon potential. In chapter 3, we calculate the tachyon potential in Berkovits' superstring field theory. In chapter 4, we look for exact solutions in a toy model. Unpublished result: we use conservation laws to calculate the level (4,8) approximation of the tachyon potential in Berkovits' superstring field theory. We verify Sen's conjecture up to 94.4%.