An Lᵖ-Spectral Multiplier Theorem with Sharp p-Specific Regularity Bound on Heisenberg Type Groups

We prove an Lᵖ L p -spectral multiplier theorem for sub-Laplacians on Heisenberg type groups under the sharp regularity condition s>d| 1/p-1/2| s > d 1 / p - 1 / 2 , where d is the topological dimension of the underlying group. Our approach relies on restriction type estimates where the multiplier is additionally truncated along the spectrum of the Laplacian on the center of the group.