Derived categories of curves of genus one and torsors over abelian varieties

Abstract

Suppose $C$ is a smooth projective curve of genus 1 over a perfect field $F$, and $E$ is its Jacobian. In the case that $C$ has no $F$-rational points, so that $C$ and $E$ are not isomorphic, $C$ is an $E$-torsor with a class $\delta (C)\in H^1(\text{Gal}(\bar{F}/F),E(\bar{F}))$. Then $\delta (C)$ determines a class $\beta \in \text{Br}(E)/\text{Br}(F)$ and there is a Fourier-Mukai equivalence of derived categories of (twisted) coherent sheaves $\mathcal{D}(C)\stackrel{\cong }{\to }\mathcal{D}(E,{\beta }^{-1})$. We generalize this result to higher dimensions; namely, we prove it also for torsors over abelian varieties.

17 pages. Some improvements from the last version, including more on why the proof works even in characteristic p, and a few additional references