Centro-Affine Differential Geometry and the Log-Minkowski Problem

Abstract

We interpret the log-Brunn-Minkowski conjecture of Böröczky-Lutwak-Yang-Zhang as a spectral problem in centro-affine differential geometry. In particular, we show that the Hilbert-Brunn-Minkowski operator coincides with the centro-affine Laplacian, thus obtaining a new avenue for tackling the conjecture using insights from affine differential geometry. As every strongly convex hypersurface in ${\mathbb{R}}^n$ is a centro-affine unit-sphere, it has constant centro-affine Ricci curvature equal to $n-2$, in stark contrast to the standard weighted Ricci curvature of the associated metric-measure space, which will in general be negative. In particular, we may use the classical argument of Lichnerowicz and a centro-affine Bochner formula to give a new proof of the Brunn-Minkowski inequality. For origin-symmetric convex bodies enjoying fairly generous curvature pinching bounds (improving with dimension), we are able to show global uniqueness in the $L^p$- and log-Minkowski problems, as well as the corresponding global $L^p$- and log-Minkowski conjectured inequalities. As a consequence, we resolve the isomorphic version of the log-Minkowski problem: for any origin-symmetric convex body $\bar{K}$ in ${\mathbb{R}}^n$, there exists an origin-symmetric convex body $K$ with $\bar{K}\subset K\subset 8\bar{K}$, so that $K$ satisfies the log-Minkowski conjectured inequality, and so that $K$ is uniquely determined by its cone-volume measure $V_K$. If $\bar{K}$ is not extremely far from a Euclidean ball to begin with, an analogous isometric result, where $8$ is replaced by $1+\epsilon$, is obtained as well.

64 pages; corrected referee comments, added for completeness statement (2b) to the equivalent statements of Theorem 2.1. Final version, to appear in Journal of European Math Society (JEMS)

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