Poincare families and line bundles on moduli stacks of G-bundles
Seminar Room 1, Newton Institute
The talk deals with the following question: Which moduli spaces of principal G-bundles over a smooth projective curve carry Poincare families (or universal families)? The obstruction is the Brauer class of the moduli stack as a gerbe over the coarse moduli scheme. This obstruction is described in terms of the root system of G. The proof uses the Picard group of the moduli stack. This is joint work with I. Biswas.