Cohomology Vanishing for Free Boundary $f$-Minimal Submanifolds in Gaussian-Weighted Euclidean Balls

Abstract

Let $M^n\subset \overline{\B_R^{n+k}}\subset \R^{n+k}$ be a compact orientable free boundary $f$-minimal submanifold of the Gaussian-weighted Euclidean ball $\left(\overline{\B_R^{n+k}},g_{\rm can},e^{-f}\dd V\right), f(x)=\frac c2 |x|^2,c\ge 0.$ We prove a cohomology vanishing theorem under the pointwise pinching condition $|A{|}^2\le \frac{n-p}{R^2},1\le p<n.$ More precisely, the space of tangential $f$-harmonic $p$-forms vanishes, and hence$H^p(M;\mathbb{R})=0.$ The proof is based on three elementary ingredients in the Gaussian-weighted ball: a weighted Hardy inequality obtained from the identity $\divf(x^T)=n-c|x|^2$, a cancellation in the weighted Weitzenböck curvature operator, and a boundary reduction showing that tangential $f$-harmonic forms satisfy the same local absolute-boundary algebra as in the unweighted case. The constant pinching threshold is independent of the Gaussian parameter $c$, and the argument also includes the unweighted case $c=0$; the strict interior positivity comes from the full Hardy--Weitzenböck coefficient rather than from the sign of $c$ alone.