Phases of N=2 Necklace Quivers
  We classify the phases of N=2 elliptic models in terms of their global properties i.e. the spectrum of line operators. We show the agreement between the field theory and the M-theory analysis and how the phases form orbits under the action of the S-duality group which corresponds to the mapping class group of the Riemann surface in M-theory. 
Antonio Amariti, Domenico Orlando, Susanne Reffert
hep-th