Sharp Estimates for the Principal Eigenvalue of the p-Operator

Abstract

Given an elliptic diffusion operator $L$ defined on a compact and connected manifold (possibly with a convex boundary in a suitable sense) with an $L$-invariant measure $m$, we introduce the non-linear $p-$operator $L_p$, generalizing the notion of the $p-$Laplacian. Using techniques of the intrinsic ${\Gamma }_2$-calculus, we prove the sharp estimate $\lambda \ge (p-1){\pi }_p^p/D^p$ for the principal eigenvalue of $L_p$ with Neumann boundary conditions under the assumption that $L$ satisfies the curvature-dimension condition BE$(0,N)$ for some $N\in [1,\infty )$. Here, $D$ denotes the intrinsic diameter of $L$. Equality holds if and only if $L$ satisfies BE$(0,1)$. We also derive the lower bound ${\pi }^2/D^2+a/2$ for the real part of the principal eigenvalue of a non-symmetric operator $L={\Delta }_g+X\cdot \nabla$ satisfying $\mathrm{BE}(a,\infty )$.

28 pages, comments welcome