Published online by Cambridge University Press: 06 February 2017
We investigate $L^{p}(\unicode[STIX]{x1D6FE})$–$L^{q}(\unicode[STIX]{x1D6FE})$ off-diagonal estimates for the Ornstein–Uhlenbeck semigroup $(e^{tL})_{t>0}$. For sufficiently large $t$ (quantified in terms of $p$ and $q$), these estimates hold in an unrestricted sense, while, for sufficiently small $t$, they fail when restricted to maximal admissible balls and sufficiently small annuli. Our counterexample uses Mehler kernel estimates.
The first author acknowledges financial support from the Australian Research Council Discovery Grant DP120103692 and the ANR project ‘Harmonic analysis at its boundaries’ ANR-12-BS01-0013. The second author acknowledges partial financial support from the Netherlands Organisation for Scientific Research (NWO) by the NWO-VICI grant 639.033.604.