Surface defects and instanton-vortex interaction

A. Gorsky; B. Le Floch; A. Milekhin; N. Sopenko

doi:10.1016/j.nuclphysb.2017.04.010

paper

Surface defects and instanton-vortex interaction

arXiv:1702.03330 · doi:10.1016/j.nuclphysb.2017.04.010

Abstract

We propose a simple formula for the 4d-2d partition function of half-BPS surface defects in $d = 4, N = 2$ gauge theories: $Z^{4d-2d} = ⟨ Z^{2d} ⟩_{4d}$ . Our results are applicable for any surface defect obtained by gauging a 2d flavour symmetry using a 4d gauge group. For defects obtained via the Higgsing procedure, our formula reproduces the recent calculation by Pan and Peelaers. For Gukov-Witten defects our results reproduce the orbifold calculation by Kanno and Tachikawa. We emphasize the role of "negative vortices" which are realized as negative D0 branes.

v1: 40 pages, 8 figures, v2: clarifications and references added