Integral pinching results for manifolds with boundary

Catino, Giovanni¹  ; Ndiaye, Cheikh Birahim²

¹ SISSA, International School for Advanced Studies, Via Beirut, 2-4, 34014 Trieste, Italia
² Mathematisches Institut der Universität Tübingen, Auf der Morgenstelle, 10, 72076 Tübingen, Germany

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 5, Tome 9 (2010) no. 4, pp. 785-813

Résumé

We prove that some Riemannian manifolds with boundary satisfying an explicit integral pinching condition are spherical space-forms. More precisely, we show that three-dimensional Riemannian manifolds with totally geodesic boundary, positive scalar curvature and an explicit integral pinching between the $L^2$-norm of the scalar curvature and the $L^2$-norm of the Ricci tensor are spherical space-forms with totally geodesic boundary. Moreover, we also prove that four-dimensional Riemannian manifolds with umbilic boundary, positive Yamabe invariant and an explicit integral pinching between the total integral of the $(Q,T)$-curvature and the $L^2$-norm of the Weyl curvature are spherical space-forms with totally geodesic boundary. As a consequence, we show that a certain conformally invariant operator, which plays an important role in Conformal Geometry, is non-negative and has trivial kernel if the Yamabe invariant is positive and verifies a pinching condition together with the total integral of the $(Q,T)$-curvature. As an application of the latter spectral analysis, we show the existence of conformal metrics with constant $Q$-curvature, constant $T$-curvature, and zero mean curvature under the latter assumptions.

Détail

Classification : 53C24, 53C20, 53C21, 53C25