Local maximizers of adjoint Fourier restriction estimates for the cone, paraboloid and sphere

Abstract

We show that, possibly after a compactification of spacetime, constant functions are local maximizers of the Tomas–Stein adjoint Fourier restriction inequality for the cone and paraboloid in every dimension, and for the sphere in dimension up to 60. For the cone and paraboloid we work from the PDE framework, which enables the use of the Penrose and the Lens transformations, which map the conjectured optimal functions into constants.