Almost periodic stochastic processes with applications to analytic number theory
Alexander Iksanov, Zakhar Kabluchko, Alexander Marynych
TL;DR
This work develops a functional limit theory for Besicovitch almost periodic functions under random translations, establishing convergence in the Besicovitch space $B_2(\mathcal{S}(f))$ to a limiting stationary random process $\mathcal{M}_f$ with a discrete spectrum. The limit admits a Fourier-series description with random coefficients, and the authors analyze its continuity, ergodicity, and tangent processes, including a Brownian-type limit under regular variation of spectral mass. They further connect these probabilistic limit objects to analytic number theory by deriving functional limit results for classical arithmetic functions such as von Mangoldt’s $\psi$, Möbius/Mertens $M$ and $L$, under RH and related conjectures (Gonek-type hypotheses). These results provide a probabilistic lens on error terms and fluctuations intimately tied to zeros of the Riemann zeta-function, offering a bridge between almost periodic analysis and number-theoretic asymptotics. The paper also proposes conjectures on lifting finite-dimensional convergence to functional convergence in spaces of continuous paths, highlighting potential broader applicability to number-theoretic problems.
Abstract
A classical fact of the theory of almost periodic functions is the existence of their asymptotic distributions. In probabilistic terms, this means that if $f$ is a Besicovitch almost periodic function and $V$ is a random variable uniformly distributed on $[-1,1]$, then the random variables $f(L\cdot V)$ converge in distribution, as $L\to\infty$, to a proper non-degenerate random variable. We prove a functional extension of this result for the random processes $(f(L\cdot V+t))_{t\in\mathbb{R}}$ in the space of Besicovitch almost periodic functions, and also in the sense of weak convergence of finite-dimensional distributions. We further investigate the properties of the limiting stationary process and demonstrate applications in analytic number theory by extending the one-dimensional results of [Limiting distributions of the classical error terms of prime number theory, Quart. J. Math. 65 (2014), 743--780] and earlier works.
