Generalized nearby cycles via relative and logarithmic $\mathscr{D}$-modules

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Hauptverfasser: Wu, Lei, Sabbah, with an appendix by Claude
Format: Preprint
Veröffentlicht: 2026
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author Wu, Lei
Sabbah, with an appendix by Claude
author_facet Wu, Lei
Sabbah, with an appendix by Claude
contents For a regular map $F$ from a complex smooth affine variety $X$ to $\mathbb A^r_\mathbb C$, we construct generalized nearby-cycle modules of a regular holonomic $\mathscr D$-module $\mathcal M$ along log strata with the log structure induced by the graph of $F$, whose relative supports are infinite unions of translated linear subvarieties of $\mathbb C^r$ determined by the zero loci of Bernstein-Sato ideals along monoid ideals. For a fixed log stratum, the nearby-cycle module corresponds to the Sabbah specialization complex of DR$(\mathcal M)$ under the relative regular Riemann-Hilbert correspondence of Fiorot-Fernandes-Sabbah, which generalizes the classical comparison theorem of Kashiwara-Malgrange for Deligne's nearby cycles. As an application, when $\mathcal M=\mathcal O_X$, we give a topological interpretation of the zero loci of Bernstein-Sato ideals of $F$ along monoid ideals under the exponential map, which answers a question of Budur-Shi-Zuo.
format Preprint
id arxiv_https___arxiv_org_abs_2602_05314
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Generalized nearby cycles via relative and logarithmic $\mathscr{D}$-modules
Wu, Lei
Sabbah, with an appendix by Claude
Algebraic Geometry
14F10, 13N10, 32C38, 32S60, 32S40, 14A21
For a regular map $F$ from a complex smooth affine variety $X$ to $\mathbb A^r_\mathbb C$, we construct generalized nearby-cycle modules of a regular holonomic $\mathscr D$-module $\mathcal M$ along log strata with the log structure induced by the graph of $F$, whose relative supports are infinite unions of translated linear subvarieties of $\mathbb C^r$ determined by the zero loci of Bernstein-Sato ideals along monoid ideals. For a fixed log stratum, the nearby-cycle module corresponds to the Sabbah specialization complex of DR$(\mathcal M)$ under the relative regular Riemann-Hilbert correspondence of Fiorot-Fernandes-Sabbah, which generalizes the classical comparison theorem of Kashiwara-Malgrange for Deligne's nearby cycles. As an application, when $\mathcal M=\mathcal O_X$, we give a topological interpretation of the zero loci of Bernstein-Sato ideals of $F$ along monoid ideals under the exponential map, which answers a question of Budur-Shi-Zuo.
title Generalized nearby cycles via relative and logarithmic $\mathscr{D}$-modules
topic Algebraic Geometry
14F10, 13N10, 32C38, 32S60, 32S40, 14A21
url https://arxiv.org/abs/2602.05314