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Main Author: Katsuda, Atsushi
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2509.16848
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author Katsuda, Atsushi
author_facet Katsuda, Atsushi
contents We develop a generalized Floquet-Bloch theory for discrete torsion-free nilpotent groups by exploiting their Malcev completions. Our main result is a branching formula that relates finite-dimensional representations of a discrete nilpotent lattice to infinite-dimensional unitary representations of its simply connected nilpotent Lie group. This generalization enables to extend the following two classical asymptotic problems (i) a Chebotarev density analogue for prime closed geodesics on compact negatively curved manifolds with nilpotent covers, and (ii) long time asymptotic expansions of heat kernels on such coverings to the nilpotent setting. As a by-product, we derive a semi-classical expansion for the Harper operator, presenting an alternative to mathematical justification of Wilkinson's formula by Helffer-Sjöstrand. We conclude by proposing several avenues for future work: extensions to general hyperbolic flows and noncompact manifolds (in particular knot complements and related quasi-morphisms), connections to modified Riemann-Hilbert problems and opers. Furthermore, we give a brief comment on asymptotic behavior of knot invariants and infinite extensions in number theory.
format Preprint
id arxiv_https___arxiv_org_abs_2509_16848
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An extension of the Floquet-Bloch theory to nilpotent groups and its applications
Katsuda, Atsushi
Differential Geometry
Mathematical Physics
Dynamical Systems
Number Theory
Probability
Primary 58J50 Secondary 58J37, 58J35, 30F99
We develop a generalized Floquet-Bloch theory for discrete torsion-free nilpotent groups by exploiting their Malcev completions. Our main result is a branching formula that relates finite-dimensional representations of a discrete nilpotent lattice to infinite-dimensional unitary representations of its simply connected nilpotent Lie group. This generalization enables to extend the following two classical asymptotic problems (i) a Chebotarev density analogue for prime closed geodesics on compact negatively curved manifolds with nilpotent covers, and (ii) long time asymptotic expansions of heat kernels on such coverings to the nilpotent setting. As a by-product, we derive a semi-classical expansion for the Harper operator, presenting an alternative to mathematical justification of Wilkinson's formula by Helffer-Sjöstrand. We conclude by proposing several avenues for future work: extensions to general hyperbolic flows and noncompact manifolds (in particular knot complements and related quasi-morphisms), connections to modified Riemann-Hilbert problems and opers. Furthermore, we give a brief comment on asymptotic behavior of knot invariants and infinite extensions in number theory.
title An extension of the Floquet-Bloch theory to nilpotent groups and its applications
topic Differential Geometry
Mathematical Physics
Dynamical Systems
Number Theory
Probability
Primary 58J50 Secondary 58J37, 58J35, 30F99
url https://arxiv.org/abs/2509.16848