Variations on the Logarithmic Laplacian Operator

The Logarithmic Laplacian Operator arises as formal derivative of fractional Laplacians at order s= 0. In this talk I will discuss properties of this operator and its relevance in the derivation of asymptotics of Dirichlet eigenvalues and eigenfunctions of fractional Laplacians in bounded domains as the order tends to zero. A further applications arises in the study of the monotonicity of solutions to fractional Poisson problems with respect to the fractional order s. As a byproduct of this study, we derive explicit bounds for the corresponding Green operator on arbitrary bounded domains which seem to be new even for the case s=1, i.e., for the classical local Dirichlet problem −Δu=f in Ω, u≡0 on ∂Ω.

This is joint work with Huyuan Chen, Sven Jarohs and Alberto Saldana.