An Extension of Nori Fundamental Group

Abstract

In this paper, we study a certain extension of Nori's fundamental group in the case where a base field is of characteristic 0 and give structure theorems about it. As a result, for a smooth projective curve with genus $g$>1, we prove that Nori's fundamental group acts faithfully on the category of unipotent bundles on the universal covering. In the case when $g=1$, we give a more finer result.

30 pages, to appear in Comm Alg, Remark 1.6 is included, dropped the smoothness assumption from the most part, changed to use a word "unipotent bundle" instead of "nilpotent bundle", at a suggestion of the referee, Section 5.2 is included

References in corpus (1)

• Fundamental gerbes

Cited by in corpus (5)

• Fundamental gerbes
• A note on certain Tannakian group schemes
• On an extension of Nori and local fundamental group schemes
• The action of the étale fundamental group scheme on the connected component of the essentially finite one
• Semifinite Bundles and the Chevalley-Weil Formula