English

Concentration between L\'evy's inequality and the Poincar\'e inequality for log-concave densities

Functional Analysis 2020-08-04 v1

Abstract

Given a suitably normalized XRnX\in\mathbb{R}^n we observe that the function θEXθ\theta\mapsto\mathbb{E}|X\cdot\theta|, defined for θSn1\theta\in S^{n-1}, admits surprisingly strong concentration far surpassing what is expected on account of L\'evy's isoperimetric inequality. Among the measures to which the above holds are all log-concave measures, for which a solution of the similar problem concerning the third marginal moments θE(Xθ)3\theta\mapsto\mathbb{E} (X\cdot \theta)^3 would imply the hyperplane conjecture.

Keywords

Cite

@article{arxiv.1706.07984,
  title  = {Concentration between L\'evy's inequality and the Poincar\'e inequality for log-concave densities},
  author = {Erez Buchweitz},
  journal= {arXiv preprint arXiv:1706.07984},
  year   = {2020}
}

Comments

Extended version including an appendix