SMOOTH TRANSFER OF KLOOSTERMAN INTEGRALS (THE ARCHIMEDEAN CASE)

• Published in: American journal of mathematics 2013-02, Vol.135 (1), p.143-182
• Main Authors: Aizenbud, Avraham, Gourevitch, Dmitry
• Format: Article
• Language: English
• Subjects: Differential equations; Geometry; Mathematical functions; Mathematical problems; Mathematics education; Proof theory
• ISSN: 0002-9327; 1080-6377; 1080-6377
• DOI: 10.1353/ajm.2013.0000

We establish the existence of a transfer, which is compatible with Kloosterman integrals, between Schwartz functions on GL n (R) and Schwartz functions on the variety of non-degenerate Hermitian forms. Namely, we consider an integral of a Schwartz function on GL n (R) along the orbits of the two sided action of the groups of upper and lower unipotent matrices twisted by a non-degenerate character. This gives a smooth function on the torus. We prove that the space of all functions obtained in such a way coincides with the space that is constructed analogously when GL n (R) is replaced with the variety of non-degenerate hermitian forms. We also obtain similar results for gl n (R). The non-Archimedean case was done by H. Jacquet (Duke Math. J., 2003) and our proof is based on the ideas of this work. However we have to face additional difficulties that appear only in the Archimedean case. Those results are crucial for the comparison of the Kuznetsov trace formula and the relative trace formula of GL n with respect to the maximal unipotent subgroup and the unitary group, as done by H. Jacquet, and by B. Feigon, E. Lapid, and O. Offen.