Dolbeault Cohomology Growth under Curvature Rank Bounds

Source abstract

Let $L$ be a smooth Hermitian holomorphic line bundle on a compact complex manifold $X$, and let $r$ be the maximal rank of its curvature. We prove that $h^q(X,L^p\otimes E)=O_\varepsilon(p^{r+\varepsilon})$ for every fixed holomorphic vector bundle $E$, every $\varepsilon>0$, and every degree $q$. No positivity, constant-rank, or Kähler assumption is imposed. Consequently, the Kodaira--Iitaka dimension satisfies $κ(L|_{X_0})\le r$ on every connected component $X_0$ of $X$. The proof retains rank identities in finite Taylor jets under successive rescalings and factors bounded Hermitian kernels without a positive lower bound on the absolute values of the nonzero curvature eigenvalues. Exact Dolbeault restriction identities yield finite-rank approximations with additive rank bounds, which control cohomology.