Higher-dimensional multifractal analysis for the cusp winding process on hyperbolic surfaces
Yuya Arima
TL;DR
The paper develops a higher-dimensional multifractal analysis for cusp windings of geodesic flow on hyperbolic surfaces with $m\ge1$ cusps. It defines the $m$-dimensional cusp-winding spectrum $b(\boldsymbol{\alpha})=\dim_H J(\boldsymbol{\alpha})$ and proves a conditional variational principle, with $b$ realized as a supremum of entropy-to-Lyapunov-ratio over invariant measures, extending prior $m=1$ results. Using a countable Markov shift with a finitely primitive matrix and thermodynamic formalism, it proves that $b$ is real-analytic on $(0,\infty)^m$ and establishes a Bowen-type relation linking the spectrum to topological pressure via a zero of $p(\boldsymbol{\alpha},\boldsymbol{q},b(\boldsymbol{\alpha}))$. In the $m=1$ case, it shows strict monotonicity of the spectrum and a maximal limit, and it demonstrates that the irregular set shares the same Hausdorff dimension as the conical limit set. Together, these results provide a comprehensive, higher-dimensional multifractal picture for cusp windings on hyperbolic surfaces and open avenues for further thermodynamic analyses in similar symbolic dynamics settings.
Abstract
We perform a multifractal analysis of the growth rate of the number of cusp windings for the geodesic flow on hyperbolic surfaces with $m \geq 1$ cusps. Our main theorem establishes a conditional variational principle for the Hausdorff dimension spectrum of the multi-cusp winding process. Moreover, we show that the dimension spectrum defined on $\mathbb{R}_{>0}^m$ is real analytic. To prove the main theorem we use a countable Markov shift with a finitely primitive transition matrix and thermodynamic formalism.
