UNITARITY OF KUO'S FOURIER–MEHLER TRANSFORM
Abstract
Kuo's Fourier–Mehler transforms {ℱΘ} form a one-parameter automorphism group of the space of white noise distributions . The adjoint transforms
form a one-parameter automorphism group of the space of test white noise functions
but do not admit unitary extensions with respect to the L2-norm induced from the Gaussian measure with variance 1. We prove that
admits an extension to a one-parameter group of unitary operators on the L2-space with respect to the Gaussian measure with variance 1/2.