Generalized parabolic structures over smooth curves with many components and principal bundles over reducible nodal curves

Abstract

Let $Y_1,\dots ,Y_l$ be smooth irreducible projective curves and let $Y$ be its disjoint union. Given a semisimple reductive algebraic group $G$ and a faithful representation $\rho :G\hookrightarrow \text{SL}(V)$ we construct a projective moduli space of $(\underline{\kappa },\delta )$-(semi)stable singular principal $G$-bundles with generalized parabolic structure of type $\underline{e}$. In case $Y$ is the normalization of a connected and reducible projective nodal curve $X$, there is a closed subscheme coarsely representing the subfunctor corresponding to descending bundles. We prove that the descent operation induces a birational, surjective and proper morphism onto the schematic closure of the space of $\delta$-stable singular principal $G$-bundles whose associated torsion free sheaf is of local type $\underline{e}$.