The Beurling and Malliavin Theorem in Several Dimensions

Abstract: The present paper is devoted to a new multidimensional generalization of the Beurling and Malliavin Theorem, which is a classical result in the Uncertainty Principle in Fourier Analysis. In more detail, we establish by an elegant but simple new method a sufficient condition for a radial function to be a Beurling and Malliavin majorant in several dimensions (this means that the function in question can be minorized by the modulus of a square integrable function which is not zero identically and which has the support of the Fourier transform included in an arbitrary small ball). As a corollary of the radial case, we also get a new sharp sufficient condition in the nonradial case. The latter result provides an answer to a question posed by L. H\"ormander. Our proof is different in the cases of odd and even dimensions. In the even dimensional case we make use of one classical formula from the theory of Bessel functions due to N. Ya. Sonin.