Moduli of twisted spin curves

Dan Abramovich; Tyler J. Jarvis

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arXiv · math/0104154

Moduli of twisted spin curves

Dan Abramovich·Tyler J. Jarvis

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Abstract

In this note we give a new, natural construction of a compactification of the stack of smooth r-spin curves, which we call the stack of stable twisted $r$-spin curves. This stack is identified with a special case of a stack of twisted stable maps of Abramovich and Vistoli. Realizations in terms of admissible G_m-spaces and Q-line bundles are given as well. The infinitesimal structure of this stack is described in a relatively straightforward manner, similar to that of usual stable curves. We construct representable morphisms from the stacks of stable twisted r-spin curves to the stacks of stable r-spin curves, and show that they are isomorphisms. Many delicate features of r-spin curves, including torsion free sheaves with power maps, arise as simple by-products of twisted spin curves. Various constructions, such as the d bar-operator of Seeley and Singer and Witten's cohomology class go through without complications in the setting of twisted spin curves.

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Dan Abramovich, Tyler J. Jarvis. 2001-04-13. Moduli of twisted spin curves. https://arxiv.org/abs/math/0104154

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