D0-brane tension in string field theory

TL;DR

This paper calculates the D0-brane tension in string field theory by modeling it as a tachyon lump on a compactified D1-brane, achieving high-precision results through level truncation.

Contribution

It introduces a method to accurately compute D0-brane tension using level truncation and identifies an optimal radius for precise agreement with theoretical predictions.

Findings

Normalized D0-brane tension is radius-independent.

Optimal radius R* yields tension matching theory at 10^{-5} accuracy.

Discusses marginal tachyon field near R→1.

Abstract

We compute the D0-brane tension in string field theory by representing it as a tachyon lump of the D1-brane compactified on a circle of radius $R$. To this aim, we calculate the lump solution in level truncation up to level L=8. The normalized D0-brane tension is independent on $R$. The compactification radius is therefore chosen in order to cancel the subleading correction $1/L^2$. We show that an optimal radius $R^*$ indeed exists and that at $R^*$ the theoretical prediction for the tension is reproduced at the level of $10^{-5}$. As a byproduct of our calculation we also discuss the determination of the marginal tachyon field at $R\to 1$.