The case of good reduction [01JW]
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The case of good reduction
When the variety has good reduction, the canonical metrics and the associated measures are fairly easy to describe. Indeed, let be the Néron model of over , an Abelian scheme. For any line bundle on there is a unique line bundle on which extends and which admits a trivialization at the section extending the given one over . By the theorem of the cube for the Abelian scheme , the isomorphism (with or , according to whether is odd or even) extends uniquely to an isomorphism . This implies that the canonical metrics are algebraic, induced by these models.
The description of the canonical measures on follows at once. Let be the point of whose reduction is the generic point of the special fiber of . Then, for any family of line bundles on , one has
We see in particular that they only depend on the classes of the line bundles modulo numerical equivalence.