Localization of a supersymmetric gauge theory in the presence of a   surface defect
  We use supersymmetric localization to compute the partition function of N=2 super-Yang-Mills on S^4 in the presence of a gauged linear sigma model surface defect on a S^2 subspace. The result takes the form of a standard partition function on S^4, with a modified instanton partition function and an additional insertion corresponding to a shifted version of the gauged linear sigma model partition function. 
Joel Lamy-Poirier
hep-th