Entropy of String States at fixed Mass and Size

TL;DR

This paper derives formulas for the entropy of free-string states based on mass, charges, and size in bosonic and superstring theories, and examines how self-interactions modify this entropy for various configurations.

Contribution

It provides a comprehensive formulation of string state entropy considering size and self-interactions, extending previous models to include BPS and non-BPS states.

Findings

Formulas for string state entropy depending on mass, charge, and size.

Analysis of self-interaction corrections to entropy.

Differences in entropy corrections between BPS and non-BPS states.

Abstract

We provide formulas for the entropy of free-string states depending on their mass, charges and size, both in bosonic and superstring theory (IIA or IIB). We properly define these quantities in full-fledged string theory. We then investigate the corrections to the entropy due to self-interactions of the string for states with fixed mass, charge and size, both for BPS and non-BPS configurations. Again, the analysis is performed using string theory techniques.