A Local Fourier-Transform Proof of Offen's Spherical Transfer Theorem

Abstract

Let $E/F$ be an unramified quadratic extension of non-archimedean local fields of characteristic zero and odd residual characteristic. Offen proved that, on the full spherical space of nondegenerate Hermitian matrices, equality of the Hironaka and Satake transforms implies Jacquet--Ye matching. We give a purely local proof of this theorem. The argument combines Jacquet's compatibility of matching with Fourier transform, the Godement--Jacquet functional equation, and Hironaka's scalar functional equation for Hermitian zeta integrals. The local proof recovers Jacquet's spherical-Hecke fundamental lemma from the unit case.