Gains of integrability and local smoothing effects for quadratic evolution equations

Paul Alphonse (1) , Joackim Bernier (2, 3)

1 UMPA-ENSL - Unité de Mathématiques Pures et Appliquées
2 LMJL - Laboratoire de Mathématiques Jean Leray
3 CNRS - Centre National de la Recherche Scientifique

We characterize geometrically the semigroups generated by non-selfadjoint quadratic differential operators $(e^{-tq^w})_{t\geq 0}$ enjoying local smoothing effects and providing gains of integrability. More precisely, we prove that the evolution operators $e^{-tq^w}$ map $L^{\mathfrak{p}}$ on $L^{\mathfrak{q}} \cap C^\infty$, for all $1\leq \mathfrak{p} \leq \mathfrak{q} \leq \infty$, if and only if the singular space of the quadratic operator $q^w$ is included in the graph of a linear map. We also provide quantitative estimates for the associated operator norms in the short-time asymptotics $0

Mots clés: quadratic operators; smoothing effects; complex Gaussian kernel; exact splittings

Domaines: Equations aux dérivées partielles [math.AP]; Analyse fonctionnelle [math.FA]

Paul Alphonse, Joackim Bernier. Gains of integrability and local smoothing effects for quadratic evolution equations. Journal of Functional Analysis, 2023, 285 (10), ⟨10.1016/j.jfa.2023.110119⟩. ⟨hal-03437144v2⟩