Geometry of the theta divisor of a compactified jacobian
arXiv:0707.4602
Abstract
We study the theta divisor of the compactified jacobian of a nodal, possibly reducible, curve. We compute its irreducible components and give it a geometric interpretation consistent with the classical Brill-Noether theory of smooth curves. Some applications on hyperelliptic stable curves are appended.
36 pages. Final version, to appear in JEMS