Scattering, determinants, hyperfunctions in relation to Gamma(1-s)/Gamma(s)

The method of realizing certain self-reciprocal transforms as (absolute) scattering, previously presented in summarized form in the case of the Fourier cosine and sine transforms, is here applied to the self-reciprocal transform f(y) 7→ H(f)(x) = ∫∞ 0 J0(2 √ xy)f(y) dy, which is isometrically equivalent to the Hankel transform of order zero and is related to the functional equations of the Dedekind zeta functions of imaginary quadratic fields. This also allows to re-prove and to extend theorems of de Branges and V. Rovnyak regarding square integrable functions which are self-or-skew reciprocal under the Hankel transform of order zero. Related integral formulae involving various Bessel functions are all established internally to the method. Fredholm determinants of the kernel J0(2 √ xy) restricted to finite intervals (0, a) give the coefficients of first and second order differential equations whose associated scattering is (isometrically) the self-reciprocal transform H, closely related to the function Γ(1−s) Γ(s) . Remarkable distributions involved in this analysis are seen to have most natural expressions as (difference of) boundary values (i.e. hyperfunctions.) The present work is completely independent from the previous study by the author on the same transform H, which centered around the Klein-Gordon equation and relativistic causality. In an appendix, we make a simple-minded observation regarding the resolvent of the Dirichlet kernel as a Hilbert space reproducing kernel. keywords: Hankel transform; Scattering; Fredholm determinants. Université Lille 1 UFR de Mathématiques Cité scientifique M2 F-59655 Villeneuve d’Ascq France [email protected]