Riesz transforms of a general Ornstein--Uhlenbeck semigroup
arXiv:2004.04022 · doi:10.1007/s00526-021-01988-6
Abstract
We consider Riesz transforms of any order associated to an Ornstein--Uhlenbeck operator , with covariance given by a real, symmetric and positive definite matrix, and with drift given by a real matrix whose eigenvalues have negative real parts. In this general Gaussian context, we prove that a Riesz transform is of weak type with respect to the invariant measure if and only if its order is at most .
29 pages. Second draft includes a new section (section 3), dealing with the definition of the negative powers of