Logarithmic Laplacian on General Riemannian Manifolds

TL;DR

This paper introduces a new Bochner integral formula for the logarithmic Laplacian on Riemannian manifolds, unifying its definition across different geometries and analyzing its properties through heat kernel estimates and spectral comparisons.

Contribution

It provides the first Bochner integral formula for the logarithmic Laplacian on complete Riemannian manifolds, extending classical results and connecting spectral and heat kernel approaches.

Findings

Derived explicit pointwise integral formulas under Ricci lower bounds

Compared spectral and heat kernel definitions, linking discrepancy to stochastic completeness

Obtained sharp heat kernel estimates on hyperbolic space and established Lp continuity

Abstract

We introduce, for the first time, a Bochner integral formula for the logarithmic Laplacian on any complete Riemannian manifold. This unified framework recovers the classical pointwise expression on Euclidean space and allows us to define logarithmic Laplacian in both compact and noncompact settings. Under a Ricci lower bound, we derive explicit pointwise integral formulas for logarithmic Laplacian, analogous to those for the fractional Laplacian. We further compare spectral versus heat kernel definitions of both fractional and logarithmic Laplacians, showing that their discrepancy is governed by the mass loss function and hence by stochastic completeness. Finally, on real hyperbolic space we exploit sharp heat kernel asymptotics to obtain precise estimates for the fractional and logarithmic kernels, identify the optimal pointwise domain for logarithmic Laplacian and establish its Lp continuity.