Weyl Transforms, the Heat Kernel and Green Function of a Degenerate Elliptic Operator

Author: Wong M.  

Publisher: Springer Publishing Company

ISSN: 0232-704X

Source: Annals of Global Analysis and Geometry, Vol.28, Iss.3, 2005-10, pp. : 271-283

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Abstract

We give a formula for the heat kernel of a degenerate elliptic partial differential operator L on 2 related to the Heisenberg group. The formula is derived by means of pseudo-differential operators of the Weyl type, {i.e.}, Weyl transforms, and the Fourier–Wigner transforms of Hermite functions, which form an orthonormal basis for L2(2). Using the heat kernel, we give a formula for the Green function of L. Applications to the global hypoellipticity of L in the sense of tempered distributions, the ultracontractivity and hypercontractivity of the strongly continuous one-parameter semigroup etL, t > 0, are given.