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Big monodromy for higher Prym-type variations

Prove that for a Galois H-cover \varphi: \Sigma_{g'}\to\Sigma_g with g≥3, the identity component of the Zariski-closure of the monodromy of R^1\pi_*\mathbb{C} equals the derived subgroup of the centralizer of H in \operatorname{Sp}_{2g'}(\mathbb{C}), and that the monodromy is an arithmetic subgroup of its Zariski-closure.

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Background

This conjecture asserts maximal possible (semisimple) monodromy for variations obtained from branched Galois covers, aligning with the slogan that monodromy groups should be as large as constraints permit. It has significant consequences for vanishing of invariants and arithmeticity.

References

Conjecture Let $H$ be a finite group, $g\geq 3$, and $\varphi: \Sigma_{g'}\to \Sigma_g$ a Galois $H$-cover. With notation as in diagram (6.1): (1) the identity component of the Zariski closure of the monodromy group of the local system $R1\pi_*\mathbb{C}$ is the derived subgroup of the centralizer of $H$ in $\on{Sp}{2g'}(\mathbb{C})$, and (2) the monodromy of $R1\pi*\mathbb{C}$ is an arithmetic subgroup of its Zariski-closure.

Motives, mapping class groups, and monodromy (2409.02234 - Litt, 3 Sep 2024) in Conjecture, Section 6.2.2