Kinky D-Strings

TL;DR

The paper analyzes a two-dimensional $\mathcal N=(4,4)$ SQED arising on a D-string in the presence of D5-branes with background fields that attract the branes. The authors show that the low-energy dynamics can be captured by a hyperKähler (or hyperKähler with torsion) massive sigma-model on the D-string's moduli space, yielding BPS kink solitons that interpolate between D5-brane vacua. They identify bound states of the D-string with F-strings with $Q$-kinks (dyonic instanton strings on the D5-brane), and they explore both Coulomb and Higgs branch descriptions, including a T-dual picture where Q-kinks map to winding modes. The results provide a controlled framework for kink solitons in eight-supercharge brane configurations and reveal non-renormalised kink masses (up to theta-angle contributions) and a rich spectrum of dyons and bound states connected via dualities.

Abstract

We study two-dimensional SQED viewed as the world-volume theory of a D-string in the presence of D5-branes with non-zero background fields that induce attractive forces between the branes. In various approximations, the low-energy dynamics is given by a hyperKahler, or hyperKahler with torsion, massive sigma-model. We demonstrate the existence of kink solutions corresponding to the string interpolating between different D5-branes. Bound states of the D-string with fundamental strings are identified with Q-kinks which, in turn, are identified with dyonic instanton strings on the D5-brane world-volume.

Figures (1)

• Figure 1: The kinky string: such soliton solutions exist whenever the string forms a bound state with the D5-branes. This can be acheived either by considering a $(1,1)$-string, or by considering a D-string in the presence of constant background RR scalar or NS-NS two form.