Boundedness of the p-primary torsion of the Brauer group of products of varieties

Let k be a field finitely generated over its prime subfield. We prove that the quotient of the Brauer group of a product of varieties over k by the sum of the images of the Brauer groups of factors has finite exponent. The bulk of the proof concerns p-primary torsion in characteristic p. Our approac...

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Bibliographic Details
Main Authors: Alexei Skorobogatov, Alexander Petrov
Format: Article
Language:English
Published: Cambridge University Press 2025-01-01
Series:Forum of Mathematics, Sigma
Subjects:
Online Access:https://www.cambridge.org/core/product/identifier/S2050509425100789/type/journal_article
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Summary:Let k be a field finitely generated over its prime subfield. We prove that the quotient of the Brauer group of a product of varieties over k by the sum of the images of the Brauer groups of factors has finite exponent. The bulk of the proof concerns p-primary torsion in characteristic p. Our approach gives a more direct proof of the boundedness of the p-primary torsion of the Brauer group of an abelian variety, as recently proved by D’Addezio. We show that the transcendental Brauer group of a Kummer surface over k has finite exponent but can be infinite when k is an infinite field of positive characteristic. This answers a question of Zarhin and the author.
ISSN:2050-5094