Off-diagonal bounds for spectral projector kernels

Abstract

We study the growth of the spectral function of the Laplace-Beltrami operator on a Riemannian manifold $M$ of dimension $n$. For $n\ge 3$ we show that for any $x\in M$ there is a full measure subset $Z_x\subset M$ such that for all $y\in Z_x$ \[E_Λ(x,y) = O_{M,x,y,\varepsilon}(Λ^{n/2}(\logΛ)^{3/2}(\log\logΛ)^{1/2+\varepsilon}). \] For $n=2$ we prove a stronger statement. For any $x\in M$ there is a full measure subset $Z_x\subset M$ such that for all $y\in Z_x$ \[E_Λ(x,y) = O_{M,x,y,\varepsilon}(Λ^{5/6}(\logΛ)^{1/6}(\log\logΛ)^{1/6+\varepsilon}) .\]

arXiv commentThis is a first draft. Comments are welcome