First Dirichlet eigenvalue and exit time moment spectra comparisons

Abstract

We prove explicit upper and lower bounds for the Poisson hierarchy, the averaged $L^1$-moment spectra $\{\dfrac{\mathcal{A}_k\left(B_R^M\right)}{\text{vol}\left(S_R^M\right)}\}_{k=1}^\infty$, and the torsional rigidity $\mathcal{A}_1(B^M_R)$ of a geodesic ball $B^M_R$ in a Riemannian manifold $M^n$ which satisfies that the mean curvatures of the geodesic spheres $S^M_r$ included in it, (up to the boundary $S^M_R$), are controlled by the radial mean curvature of the geodesic spheres $S^\omega_r(o_\omega)$ with same radius centered at the center $o_\omega$ of a rotationally symmetric model space $M^n_\omega$. As a consecuence, we prove a first Dirichlet eigenvalue $\lambda_1(B^M_R)$ comparison theorem and show that equality with the bound $\lambda_1(B^\omega_R(o_\omega))$, (where $B^\omega_r(o_\omega)$ is the geodesic $r$-ball in $M^n_\omega$), characterizes the $L^1$-moment spectrum $\{\mathcal{A}_k(B^M_R)\}_{k=1}^\infty$ as the sequence $\{\mathcal{A}_k(B^\omega_R)\}_{k=1}^\infty$ and vice-versa.