Abstract
We prove a CR version of the Obata’s result for the first eigenvalue of the sub-Laplacian in the setting of a compact strictly pseudoconvex pseudohermitian manifold which satisfies a Lichnerowicz type condition and has a divergence free pseudohermitian torsion. We show that if the first positive eigenvalue of the sub-Laplacian takes the smallest possible value then, up to a homothety of the pseudohermitian structure, the manifold is the standard Sasakian unit sphere. We also give a version of this theorem using the existence of a function with traceless horizontal Hessian on a complete, with respect to Webster’s metric, pseudohermitian manifold.
Similar content being viewed by others
Reference
Baudoin, F., Garofalo, N.: Curvature-dimension inequalities and Ricci lower bounds for sub-Riemannian manifolds with transverse symmetries. arXiv:1101.3590
Baudoin, F., Kim, B.: Sobolev, Poincare and isoperimetric inequalities for subelliptic diffusion operators satisfying a generalized curvature dimension inequality. arXiv:1203.3789
Barletta E: The Lichnerowicz theorem on CR manifolds. Tsukuba J. Math. 31, 77–97 (2007)
Bedford E: \({(\partial\bar\partial)_b}\) and the real parts of CR functions. Indiana Univ. Math. J. 29, 333–340 (1980)
Bedford E., Federbush P: Pluriharmonic boundary values. Tohoku Math. J. 2(26), 505–511 (1974)
Boeckx E., Cho J.T: \({\eta}\) -parallel contact metric spaces. Differ. Geom. Appl. 22, 275–285 (2005)
Cao J., Chang S.-C: Pseudo-Einstein and Q-flat metrics with eigenvalue estimates on CR-hypersurfaces. Indiana Univ. Math. J. 56, 2839–2857 (2007)
Chang S.-C., Chiu H.-L: Nonnegativity of the CR Paneitz operator and its application to the CR Obata’s theorem. J. Geom. Anal. 19, 261–287 (2009)
Chang S.-C., Chiu H.-L: On the CR analogue of Obata’s theorem in a pseudohermitian 3-manifold. Math. Ann. 345, 33–51 (2009)
Chang S.-C., Chiu H.-L: On the estimate of the first eigenvalue of a sublaplacian on a pseudohermitian 3-manifold. Pac. J. Math. 232, 269–282 (2007)
Chang S.-C., Cheng J.-H., Chiu H.-L: A fourth order curvature flow on a CR 3-manifold. Indiana Univ. Math. J. 56, 1793–1826 (2007)
Chanillo S., Chiu H.-L., Yang P: Embeddability for the three dimensional CR manifolds and CR Yamabe invariants. Duke Math. J. 161, 2909–2921 (2012)
Chang S.-C., Tie J., Wu C.-T: Subgradient estimate and Liouville-type theorem for the CR heat equation on Heisenberg groups. Asian J. Math. 14, 41–72 (2010)
Chang S.-C., Wu C.-T: The entropy formulas for the CR heat equation and their applications on pseudohermitian (2n + 1)-manifolds. Pac. J. Math. 246, 1–29 (2010)
Chang, S.-C., Wu, C.-T.: The diameter estimate and its application to CR Obata’s Theorem on closed pseudohermitian (2n + 1)-manifolds. Trans. Am. Math. Soc. (to appear)
Chiu H.-L: The sharp lower bound for the first positive eigenvalue of the subLaplacian on a pseudohermitian 3-manifold. Ann. Global Anal. Geom. 30, 81–96 (2006)
Dragomir, S., Tomassini, G.: Differential geometry and analisys on CR manifolds. Progress in Mathematics, vol. 246. Birkhäuser, Boston (2006)
Gallot S: Équations différentielles caracteristiques de la sphére. Ann. Sci. École Norm. Sup. 4(12), 235–267 (1979)
Gover A.R., Graham C.R: CR invariant powers of the sub-Laplacian. J. Reine Angew. Math. 583, 1–27 (2005)
Graham C.R., Lee J.M: Smooth solutions of degenerate Laplacians on strictly pseudoconvex domains. Duke Math. J. 57, 697–720 (1988)
Graham C.R: The Dirichlet problem for the Bergman Laplacian. I and II. Commun. Partial Differ. Equ. 8(433–476), 563–641 (1983)
Greenleaf A: The first eigenvalue of a subLaplacian on a pseudohermitian manifold. Commun. Partial Differ. Equ. 10, 191–217 (1985)
Hirachi, K.: Scalar pseudo-hermitian invariants and the Szegö kernel on three-dimensional CR manifolds. In: Complex Geometry, 1990 Osaka Conf. Proc. Marcel Dekker Lect. Notes Pure Appl. Math., vol. 143, pp. 67–76 (1993)
Hladky, R.: Bounds for the first eigenvalue of the horizontal Laplacian in positively curved sub-Riemannian manifolds. arXiv:1111.5004.
Ivanov, S., Minchev, I., Vassilev, D.: Quaternionic contact Einstein structures and the quaternionic contact Yamabe problem. Mem AMS (accepted)
Ivanov, S., Petkov, A., Vassilev, D.: The sharp lower bound of the first eigenvalue of the sub-Laplacian on a quaternionic contact manifold. J. Geom. Anal. (accepted)
Ivanov, S., Vassilev, D.: An Obata-type theorem on a three dimensional CR manifold. arXiv:1208.1240.
Ivanov, S., Vassilev, D.: Extremals for the Sobolev Inequality and the Quaternionic Contact Yamabe Problem. Imperial College Press Lecture Notes. World Scientific, Hackensack (2011)
Ivanov S., Vassilev D., Zamkovoy S: Conformal Paracontact curvature and the local flatness theorem, Geom. Dedicata 144, 79–100 (2010)
Lichnerowicz, A.: Géométrie des groupes de transformations. Travaux et Recherches Mathematiques III. Dunod, Paris (1958)
Lee J: Pseudo-einstein structures on CR manifolds. Am. J. Math. 110, 157–178 (1988)
Lempert L: On three-dimensional Cauchy–Riemann manifolds. J. Am. Math. Soc. 5, 923–969 (1992)
Li S.-Y., Luk H.-S: The sharp lower bound for the first positive eigenvalue of a sub-Laplacian on a pseudo-Hermitian manifold. Proc. Am. Math. Soc. 132, 789–798 (2004)
Li, S.-Y., Wang, X.: An Obata type theorem in CR geometry. arXiv:1207.4033, version 1.
Li, S.-Y., Wang, X.: An Obata type theorem in CR geometry. arXiv:1207.4033, version 2.
Obata M: Certain conditions for a Riemannian manifold to be iosometric with a sphere. J. Math. Soc. Japan 14, 333–340 (1962)
Petit R: Mok-Siu-Yeung type formulas on contact locally sub-symmetric spaces. Ann. Global Anal. Geom. 35, 1–37 (2009)
Tanaka, N.: A differential geometric study on strongly pseudo-convex manifolds. Lectures in Mathematics. Department of Mathematics, Kyoto University, Tokyo (1975)
Webster, S.M.: Real hypersurfaces in complex space, Thesis. University of California, California (1975)
Webster S.M: Pseudo-hermitian structures on a real hypersurface. J. Differ. Geom. 13, 25–41 (1979)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ivanov, S., Vassilev, D. An Obata type result for the first eigenvalue of the sub-Laplacian on a CR manifold with a divergence-free torsion. J. Geom. 103, 475–504 (2012). https://doi.org/10.1007/s00022-013-0145-7
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00022-013-0145-7