Abstract
Given an irreducible normal Noetherian scheme and a finite Galois extension of the field of rational functions, we discuss the comparison of the categories of vector bundles on the scheme and equivariant vector bundles on the integral closure in the extension. This is well understood in the tame case (geometric stabilizer groups of order invertible in the local rings), so we focus on the wild (non-tame) case, which may be reduced to the case of cyclic extensions of prime order. In this case, under an additional flatness hypothesis, we give a characterization of the equivariant vector bundles that arise by base change from vector bundles on the scheme.
Similar content being viewed by others
References
Abramovich, D., Vistoli, A.: Compactifying the space of stable maps. J. Amer. Math. Soc. 15(1), 27–75 (2002)
Alper, J.: Good moduli spaces for Artin stacks. Ann. Inst. Fourier (Grenoble) 63(6), 2349–2402 (2013)
Alper, J., Kresch, A.: Equivariant versal deformations of semistable curves. Michigan Math. J. 65(2), 227–250 (2016)
Arbarello, E., Cornalba, M., Griffiths, P.A.: Geometry of Algebraic Curves. Vol. II. Grundlehren der Mathematischen Wissenschaften, vol. 268. Springer, Heidelberg (2011)
Deligne, P., Mumford, D.: The irreducibility of the space of curves of given genus. Publ. Math. Inst. Hautes Études Sci. 36, 75–109 (1969)
Erez, B.: The Galois structure of the square root of the inverse different. Math. Z. 208(2), 239–255 (1991)
Grothendieck, A.: Éléments de géométrie algébrique, II: Étude globale élémentaire de quelques classes de morphismes. Publ. Math. Inst. Hautes Études Sci. 8 (1961)
Grothendieck, A.: Éléments de géométrie algébrique, III: Étude cohomologique des faisceaux cohérents. Publ. Math. Inst. Hautes Études Sci. 11 (1961)
Grothendieck, A. (dirigé): Revêtements Étales et Groupe Fondamental (SGA 1). Lecture Notes in Mathematics, vol. 224. Springer, Berlin (1971)
Hartshorne, R.: Stable reflexive sheaves. Math. Ann. 254(2), 121–176 (1980)
Hassett, B., Kresch, A., Tschinkel, Yu.: Stable rationality and conic bundles. Math. Ann. 365(3–4), 1201–1217 (2016)
Keel, S., Mori, S.: Quotients by groupoids. Ann. Math. 145(1), 193–213 (1997)
Köck, B.: Galois structure of Zariski cohomology for weakly ramified covers of curves. Amer. J. Math. 126(5), 1085–1107 (2004)
Kresch, A., Tschinkel, Yu.: Models of Brauer–Severi surface bundles. Moscow Math. J. 19(3), 549–595 (2019)
Kresch, A., Vistoli, A.: On coverings of Deligne–Mumford stacks and surjectivity of the Brauer map. Bull. London Math. Soc. 36(2), 188–192 (2004)
Laumon, G., Moret-Bailly, L.: Champs Algébriques. Ergebnisse der Mathematik und ihrer Grenzgebiete, vol. 39. Springer, Berlin (2000)
Mac Lane, S.: Homology. Die Grundlehren der mathematischen Wissenschaften, vol. 114. Springer, Berlin (1963)
Milne, J.S.: Étale Cohomology. Princeton Mathematical Series, vol. 33. Princeton University Press, Princeton (1980)
Pink, R.: Euler–Poincaré formula in equal characteristic under ordinariness assumptions. Manuscripta Math. 102(1), 1–24 (2000)
Raynaud, M., Gruson, L.: Critères de platitude et de projectivité: Techniques de “platification” d’un module. Invent. Math. 13, 1–89 (1971)
Romagny, M., Rydh, D., Zalamanksy, G.: The complexity of a flat groupoid. Doc. Math. 23, 1157–1196 (2018)
Serre, J.-P.: Corps Locaux. Publications de l’Institut de Mathématique de l’Université de Nancago, vol. 8. Hermann, Paris (1962)
Vinatier, S.: Structure galoisienne dans les extensions faiblement ramifiées de \({\mathbb{Q}}\). J. Number Theory 91(1), 126–152 (2001)
Acknowledgements
The author is grateful to David Rydh for valuable comments.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Kresch, A. Descent of vector bundles under wildly ramified extensions. European Journal of Mathematics 6, 1255–1263 (2020). https://doi.org/10.1007/s40879-019-00394-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40879-019-00394-9