Dimension independent Bernstein-Markov inequalities in Gauss space

Abstract

We obtain the following dimension independent Bernstein-Markov inequality in Gauss space: for each $1\leq p<\infty$ there exists a constant $C_p>0$ such that for any $k\geq 1$ and all polynomials $P$ on $\mathbb{R}^{k}$ we have $$ \| \nabla P\|_{L^{p}(\mathbb{R}^{k}, \mathrm{d}\gamma_k)} \leq C_p (\mathrm{deg}\, P)^{\frac{1}{2}+\frac{1}{\pi}\arctan\left(\frac{|p-2|}{2\sqrt{p-1}}\right)}\|P\|_{L^{p}(\mathbb{R}^{k}, \mathrm{d}\gamma_k)}, $$ where $\mathrm{d}\gamma_k$ is the standard Gaussian measure on $\mathbb{R}^{k}$. We also show that under some mild growth assumptions on any function $B \in C^{2}((0,\infty))\cap C([0,\infty))$ with $B', B''>0$ we have $$ \int_{\mathbb{R}^{k}} B\left( |LP(x)|\right) \mathrm{d}\gamma_k(x) \leq \int_{\mathbb{R}^{k}} B\left( 10 (\mathrm{deg}P)^{\alpha_{B}}|P(x)|\right)\mathrm{d}\gamma_k(x) $$ where $L=\Delta-x\cdot \nabla $ is the generator of the Ornstein-Uhlenbeck semigroup and $$ \alpha_{B} =1+\frac{2}{\pi} \arctan\left(\frac{1}{2}\sqrt{\sup_{s \in (0,\infty)}\left\{\frac{sB''(s)}{B'(s)}+\frac{B'(s)}{sB''(s)}\right\}-2}\right). $$