Fonctions harmoniques positives sur certains groupes de Lie résolubles connexes
Fourier transform of Schwartz functions on the Heisenberg group
Let H₁ be the 3-dimensional Heisenberg group. We prove that a modified version of the spherical transform is an isomorphism between the space 𝓢ₘ(H₁) of Schwartz functions of type m and the space 𝓢(Σₘ) consisting of restrictions of Schwartz functions on ℝ² to a subset Σₘ of the Heisenberg fan with |m| of the half-lines removed. This result is then applied to study the case of general Schwartz functions on H₁.
Fourier-Wigner transforms and Liouville's theorems for the sub-Laplacian on the Heisenberg group
The sub-Laplacian on the Heisenberg group is first decomposed into twisted Laplacians parametrized by Planck's constant. Using Fourier-Wigner transforms so parametrized, we prove that the twisted Laplacians are globally hypoelliptic in the setting of tempered distributions. This result on global hypoellipticity is then used to obtain Liouville's theorems for harmonic functions for the sub-Laplacian on the Heisenberg group.
Functional calculus of Lie groups and wave propagation.
Fundamental solutions for translation and rotation invariant differential operators on the Heisenberg group
Fundamental solutions of differential operators on homogeneous manifolds of negative curvature and related Riesz transforms
Funktionenalgebren auf Bahnen nilpotenter Gruppen