Sharp quantitative stability of the Ashbaugh--Benguria inequality
Abstract
We establish sharp quantitative stability of the Ashbaugh--Benguria inequality on bounded convex domains in βn. After volume and centroid normalization, the eigenvalue-ratio deficit controls the squared Hβ1/2(πnβ1) norm of the radial displacement from the unit sphere. This yields the optimal exponent 5/2 for the Fraenkel asymmetry and, for small deficits, the optimal exponent (n+4)/2 for the normalized Hausdorff distance. All three exponents are sharp even among smooth strictly convex domains whose principal curvatures lie in [1/2,2]. In particular, the quadratic Fraenkel-asymmetry estimate proposed by Brasco and De Philippis (2017, Open Problem 7.65) fails. We also determine the optimal stability exponents under higher-order radial regularity bounds.
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BibTeX
@misc{huang2026sharp,
title = {{Sharp quantitative stability of the Ashbaugh--Benguria inequality}},
author = {Long-Han Huang and Yuxuan Zhou and Wenming Zou},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31223},
eprint = {2610.31223},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31223},
}
RIS
TY - UNPB
TI - Sharp quantitative stability of the Ashbaugh--Benguria inequality
AU - Long-Han Huang
AU - Yuxuan Zhou
AU - Wenming Zou
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31223
UR - https://arxiv.org/abs/2610.31223
AB - We establish sharp quantitative stability of the Ashbaugh--Benguria inequality on bounded convex domains in β^n. After volume and centroid normalization, the eigenvalue-ratio deficit controls the squared H^β1/2(π^nβ1) norm of the radial displacement from the unit sphere. This yields the optimal exponent 5/2 for the Fraenkel asymmetry and, for small deficits, the optimal exponent (n+4)/2 for the normalized Hausdorff distance. All three exponents are sharp even among smooth strictly convex domains whose principal curvatures lie in [1/2,2]. In particular, the quadratic Fraenkel-asymmetry estimate proposed by Brasco and De Philippis (2017, Open Problem 7.65) fails. We also determine the optimal stability exponents under higher-order radial regularity bounds.
ER -