Siu's curvature positivity and $L^2$ extension theorems for $(p,q)$-forms

Abstract

In this paper, we introduce Siu's curvature operator \(A^E_{p,q}\) for vector-bundle-valued differential forms on Kähler manifolds. When $p=n$, this operator reduces to the classical Akizuki--Nakano curvature operator. We first characterize the semipositivity of \(A^E_{p,q}\) in terms of an optimal \(L^2\)-estimate condition for the \(\bar\partial\)-operator, and then prove an Ohsawa--Takegoshi-type extension theorem for \(E\)-valued \((p,q)\)-forms under the curvature condition \(A^E_{p,q+1}\geq0\), using a new twisted basic estimate adapted to this setting. As an application, we prove the local freeness of the higher direct image sheaf \(R^q s_*(Ω^p_{X/ B_m}\otimes E)\) under the curvature conditions $A_{p,q+1}^E\ge 0$ and $A_{p,q}^E\ge 0$, where $s:X\to B_m:=\{t\in {\mathbb{C}}^m:|t|<1\}$ is a proper holomorphic submersion from a Kähler manifold $X$, and $E$ is a Hermitian holomorphic vector bundle.

The author has withdrawn this manuscript after identifying a gap in the argument concerning the higher direct image application. In addition, after a natural change of coefficient bundle, the main \(L^2\)-estimate and extension results follow from existing results. The manuscript will not be pursued in its present form