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Setup:

Let $R$ be a finitely generated subring of $\mathbb{C}$. Let $X \rightarrow \mathbb{A}^1_R$ be a proper morphism of $R$-varieties, smooth except over a rational point $s \in \mathbb{A}^1_R$ that has finite residue field $\kappa$.

Let $K$ be the fraction field of the henselization of $\mathbb{A}^1_{\kappa}$ at $s$. Let $l$ be a prime different from $\text{char}(\kappa)$. Assume that the inertia of $\text{Gal}(K)$ acts unipotently on $H^i(X_{\bar{K}},\mathbb{Q}_l)$.

Let $\tilde{\mathbb{A}}^1_{\mathbb{C}}$ be the universal covering space of $(\mathbb{A}^1_{\mathbb{C}})^{\text{an}}$, and let $\tilde{X}_{\mathbb{C}} = X_{\mathbb{C}} \times_{\mathbb{A}^1_{\mathbb{C}}} \tilde{\mathbb{A}}^1_{\mathbb{C}}$.

On one hand, there is a (Galois-theoretic) weight-monodromy filtration on $H^i(X_{\bar{K}},\mathbb{Q}_l)$.

On another hand, there is a (Hodge-theoretic) weight-monodromy filtration on $H^i(\tilde{X}_{\mathbb{C}},\mathbb{Q})$.

Question: Is it possible to (canonically) compare these analogous filtrations directly, e.g. using base change theorems?

(Also, corrections to any mistakes in the formulations above are welcome.)

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  • $\begingroup$ possibly related: mathoverflow.net/q/332973/141498 $\endgroup$
    – user141498
    Commented Jun 10, 2019 at 16:51
  • $\begingroup$ also: mathoverflow.net/a/269230/141498 $\endgroup$
    – user141498
    Commented Jun 10, 2019 at 16:54
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    $\begingroup$ doesn’t this follow from the fact that the monodromy is the same ( via comparison to singular cohomology)? $\endgroup$
    – Will Sawin
    Commented Jun 10, 2019 at 17:28

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