A rigid local system with monodromy group 2.J_2

摘要

We exhibit a rigid local system of rank six on the affine line in characteristic p = 5 whose arithmetic and geometric monodromy groups are the finite group 2.J(2) (J(2) the Hall-Janko sporadic group) in one of its two (Galois-conjugate) irreducible representation of degree six. (C) 2019 Elsevier Inc. All rights reserved.