The Quarterly Journal of Mathematics Advance Access published online on May 15, 2009
The Quarterly Journal of Mathematics, doi:10.1093/qmath/hap017
DIFFERENTIAL OPERATORS ON AN AFFINE CURVE: IDEAL CLASSES AND PICARD GROUPS

Department of Mathematics, Cornell University, Ithaca, NY 14853, USA

Mathematical Institute, 24–29 St Giles, Oxford OX1 3LB, UK
Corresponding author. E-mail: wilsong{at}maths.ox.ac.uk
Received 4 November 2008;
| Abstract |
|---|
Let X be a smooth complex affine curve, and let
be the space of right ideal classes in the ring
of differential operators on X. We introduce and study a fibration
:
Pic X. We relate this fibration to the corresponding one in the classical limit, and derive an integer invariant n which indexes the decomposition of the fibres of
into Calogero–Moser spaces. We also study the action of the group Pic
on our fibration; and we explain how to define
in the framework of the Grassmannian description of
due to Cannings and Holland.
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