On Marginal Deformations in Superstring Field Theory

TL;DR

This paper investigates the effective potential for Wilson line marginal deformations in superstring field theory, analyzing BPS and non-BPS D-branes, and provides insights into gauge field masses in stable vacua.

Contribution

It applies level truncated superstring field theory to compute the effective potential for marginal deformations, revealing new features of the potential and gauge field mass in different D-brane configurations.

Findings

Effective potential becomes flatter with higher levels in the M-branch.

V-branch exists only within a finite deformation range.

Gauge field mass remains non-zero and stabilizes at higher levels.

Abstract

We use level truncated superstring field theory to obtain the effective potential for the Wilson line marginal deformation parameter which corresponds to the constant vacuum expectation value of the U(1) gauge field on the D-brane in a particular direction. We present results for both the BPS and the non-BPS D-brane. In the case of non-BPS D-brane the effective potential has branches corresponding to the extrema of the tachyon potential. In the branch with vanishing tachyon vev (M-branch), the effective potential becomes flatter as the level of the approximation is increased. The branch which corresponds to the stable vacuum after the tachyon has condensed (V-branch) exists only for a finite range of values of marginal deformation parameter. We use our results to find the mass of the gauge field in the stable tachyonic vacuum. We find this mass to be of a non-zero value which seems to stabilize as the level approximation is improved.