Elliptic genera of monopole strings
  We obtain the elliptic genera of monopole strings in 5d MSYM. We find agreement with corresponding TST-dual dyonic-instanton single particle indices in 1110.2175. We make use of (2,2) superconformal algebra and its spectral flow, and the agreement can therefore be taken as evidence that monopole string (4,4) sigma models are exactly quantum superconformal. 
Dongsu Bak and Andreas Gustavsson
hep-th