ku-theoretic spectral decompositions for spheres and projective spaces

Abstract

Ben-Zvi--Sakellaridis--Venkatesh described a conjectural extension of the geometric Satake equivalence to spherical varieties, whose spectral decomposition is described by Hamiltonian varieties. The goal of this article is to study their conjecture, especially in the case of spherical varieties of relative rank 1, using tools from homotopy theory. Our discussion relates their conjecture to classical topics in homotopy theory such as the EHP sequence and Hopf fibrations, as well as more modern topics such as Hochschild (co)homology. We will also study an analogue of the derived geometric Satake equivalence and of the Ben-Zvi--Sakellaridis--Venkatesh conjecture with coefficients in connective complex K-theory. In this generalized setting, the dual group (a la Langlands, Gaitsgory--Nadler, Sakellaridis--Venkatesh, Knop--Schalke) remains unchanged, but the specific dual "representation" of the dual group changes. On the spectral/Langlands dual side, we expect that the appropriate replacement of Hamiltonian varieties are given by what we term "ku-Hamiltonian varieties"; this is a notion interpolating between Hamiltonian and quasi-Hamiltonian varieties (a la Alekseev--Malkin--Meinrenken). Finally, we suggest possible generalizations to more exotic cohomology theories such as complex cobordism.