Gukov, Sergei Max Planck Institute for Mathematics, Max Planck Society;
Gukov_2d index_oa_2014.pdf (Any fulltext), 769KB
Gadde, A., & Gukov, S. (2014). 2d index and surface operators. Journal of High Energy Physics, 3: 80. doi:10.1007/JHEP03(2014)080.