Tuesday, April 9, 2013

1105.4830 (Johan Martens et al.)

Compactifications of reductive groups as moduli stacks of bundles    [PDF]

Johan Martens, Michael Thaddeus
Let G be a split reductive group. We introduce the moduli problem of "bundle chains" parametrizing framed principal G-bundles on chains of lines. Any fan supported in a Weyl chamber determines a stability condition on bundle chains. Its moduli stack provides an equivariant toroidal compactification of G. All toric orbifolds may be thus obtained. Moreover, we get a canonical compactification of any semisimple G, which agrees with the wonderful compactification in the adjoint case, but which in other cases is an orbifold. Finally, we describe the connections with Losev-Manin's spaces of weighted pointed curves and with Kausz's compactification of GL(n).
View original: http://arxiv.org/abs/1105.4830

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