On the modular interpretation of the Nagaraj-Seshadri locus
Seminar Room 1, Newton Institute
We will survey constructions of moduli spaces for principal bundles on nodal curves over the complex numbers. This includes a moduli space for torsion free sheaves A of rank r and degree zero on an irreducible nodal curve X which are endowed with a homomorphism d: ∧^r A → O_X which is an isomorphism away from the node. It is a degeneration of the moduli space of SL_r(C)-bundles on a smooth curve. In many cases, this moduli space puts a scheme structure on the "Nagaraj-Seshadri locus"
inside the moduli space of semistable torsion free sheaves of rank r and degree zero.