{ "id": "0901.1455", "version": "v1", "published": "2009-01-11T16:31:32.000Z", "updated": "2009-01-11T16:31:32.000Z", "title": "The maximal operator associated to a non-symmetric Ornstein-Uhlenbeck semigroup", "authors": [ "G. Mauceri", "L. Noselli" ], "comment": "20 pages, to appear in J Fourier Anal Appl, available on line at http://www.springerlink.com", "categories": [ "math.FA" ], "abstract": "Let (H_t) be the Ornstein-Uhlenbeck semigroup on R^d with covariance matrix I and drift matrix \\lambda(R-I), where \\lambda>0 and R is a skew-adjoint matrix and denote by \\gamma_\\infty the invariant measure for (H_t). Semigroups of this form are the basic building blocks of Ornstein-Uhlenbeck semigroups which are normal on L^2(\\gamma_\\infty). We prove that if the matrix R generates a one-parameter group of periodic rotations then the maximal operator associated to the semigroup is of weak type 1 with respect to the invariant measure. We also prove that the maximal operator associated to an arbitrary normal Ornstein-Uhlenbeck semigroup is bounded on L^p(\\gamma_\\infty) if and only if 1