Exponential Motives and Arithmetic Gevrey Series

ongoing

Exponential motives are a powerful tool for the study of a host of objects attached to an algebraic variety along with a regular function, ranging from exponential sums over finite fields in analytic number theory to Landau-Ginzburg models in mirror symmetry. This project revolves around applications of the abstract theory of exponential motives to concrete problems pertaining to arithmetic Gevrey series, after my recent breakthrough in solving a 1929 question by Siegel. Arithmetic Gevrey series are power series with algebraic coefficients that satisfy a differential equation and certain growth conditions of arithmetic nature. Depending on the specific shape of these conditions, they come into three main flavours: G-functions, E-functions, and Э-functions. We plan to make significant progress on three interrelated questions about arithmetic Gevrey series: What are the transcendence properties of their special values? What is the nature of the differential equations they satisfy? Do they admit integral representations coming from geometry? The most important examples of G-functions arise from period functions of one-parameter families of algebraic varieties. A geometric interpretation of E-functions and their differential equations was lacking until exponential motives entered the scene. We will systematically exploit the new possibilities they offer to make the differential Galois group act on special values of E-functions, elucidate the local-to-global nature of index theorems for E-operators, prove general structure results for Hodge loci of exponential motives, and reconcile the Siegel-Shidlovsky theorem with Wüstholz’s analytic subgroup theorem, with a view to separating special values of E-functions and G-functions. We will also advance our understanding of the relation between G-functions and hypergeometric series, as well as the arithmetic of regularised special values of Э-functions.