Let Ω ⊂ C 2 be a strictly pseudoconvex domain and M = ∂Ω be a smooth, compact and connected CR manifold embedded in C 2 with the CR structure induced from C 2 . The main result proved here is as follows. Assume the CR structure of M has zero torsion. Then if we make a small real-analytic deformation of the CR structure of M along embeddable directions, the CR structures along the deformation path continue to have nonnegative Paneitz operators. We also show that any ellipsoid in C 2 has positive Webster curvature.
introductionThroughout this paper, we will use the notation and terminology in ([14]) unless otherwise specified. Let (M, J, θ) be a smooth, closed and connected three-dimensional pseudohermitian manifold, where θ is a contact form and J is a CR structure compatible with the contact bundle ξ = ker θ. The CR structure J decomposes C ⊗ξ into the direct sum of T 1,0 and T 0,1 which are eigenspaces of J with respect to i and −i, respectively. The Levi form , L θ is the Hermitian form on T 1,0 defined by Z, W L θ = −i dθ, Z ∧ W . We can extend , L θ to T 0,1 by defining Z, W L θ = Z, W L θ for all Z, W ∈ T 1,0 . The Levi form induces a natural Hermitian form on the dual bundle of T 1,0 , denoted by , L * θ , and hence on all the induced tensor bundles. Integrating the hermitian form (when acting on sections) over M with respect to the volume form dV = θ ∧ dθ, we get an inner product on the space of sections of each tensor bundle. We denote the inner product by the notation , . For2000 Mathematics Subject Classification. Primary 32V05, 32V20; Secondary 53C56. v19.