A converse of Berndtsson's theorem on the positivity of direct images

Fuente: arXiv
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Main Authors: Xu, Wang, Yang, Hui
Format: Preprint
Published: 2026
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_version_ 1866909994491838464
author Xu, Wang
Yang, Hui
author_facet Xu, Wang
Yang, Hui
contents Berndtsson's famous theorem asserts that, for a compact Kähler fibration $p:X\to Y$, the direct image bundle $p_*(K_{X/Y}\otimes L)$ of a semi-positive Hermitian holomorphic line bundle $L\to X$ is Nakano semi-positive. As a continuation of our previous work, we prove a converse of Berndtsson's theorem in the case of a projective fibration: if $p_*(K_{X/Y}\otimes L\otimes E)$ is Griffiths semi-positive for every semi-positive Hermitian holomorphic line bundle $E\to X$, then the curvature of $L$ must be semi-positive.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12825
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A converse of Berndtsson's theorem on the positivity of direct images
Xu, Wang
Yang, Hui
Complex Variables
32F17, 32L05, 32U05
Berndtsson's famous theorem asserts that, for a compact Kähler fibration $p:X\to Y$, the direct image bundle $p_*(K_{X/Y}\otimes L)$ of a semi-positive Hermitian holomorphic line bundle $L\to X$ is Nakano semi-positive. As a continuation of our previous work, we prove a converse of Berndtsson's theorem in the case of a projective fibration: if $p_*(K_{X/Y}\otimes L\otimes E)$ is Griffiths semi-positive for every semi-positive Hermitian holomorphic line bundle $E\to X$, then the curvature of $L$ must be semi-positive.
title A converse of Berndtsson's theorem on the positivity of direct images
topic Complex Variables
32F17, 32L05, 32U05
url https://arxiv.org/abs/2601.12825