Line Operators in 4d N=2 Supersymmetric Field Theories
Gregory Moore
I will describe work in progress with Davide Gaiotto and Andy Neitzke
on the relations between supersymmetric line operators in d=4, N=2 theories
and "Darboux coordinates" on Seiberg-Witten moduli spaces. We introduce
an index known as the "protected spin character of framed BPS states" which
enables us to give a physical proof of the ``motivic Kontsevich-Soibelman
wall crossing formula'' and to describe noncommutative deformations of the
algebra of the Darboux functions.