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In the article "La conjecture de Weil", Deligne proves that for the primitive cohomology of a universal family $f:X \rightarrow S$ for $M_{d,n}$ the moduli stack of hypersurfaces of degree $d$ in $\mathbb{P}^{n}$ (over $\mathbb{C}$ ), the monodromy representation is irreducible. Someone has told me that this result is extended by Carlson to local systems obtained as $i$-th eigenspaces of the variation of Hodge structures $(R^{n}g_{*}\mathbb{C}_{Z})i$ of the family of $d$-fold cyclic coverings $g:Z \rightarrow S$ (branched along $X$) for certain values of $d$ and $i$. I could not find the exact result in Carlson's work. Can anyone tell me for which values of $d$ and $i$, the monodromy of eigenspace is irreducible?

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You should look at Carlson and Toledo "Discriminant complements and kernels of monodromy reps" Duke 1999. Also you left out "conjecture" after "La" – Donu Arapura Jun 27 '12 at 13:36
Thank you for your comment. I have looked at that papaer but it seems that this result is not explicitely mentioned there, so I thought maybe someone knows the exact result. – Jack Jun 27 '12 at 13:42

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