On the number of poles of the dynamical zeta functions for billiard flow
Vesselin Petkov
TL;DR
This work analyzes the pole structure of meromorphically continued dynamical zeta functions $\\eta_N$, $\\eta_D$ for billiard flows around multiple strictly convex obstacles under a non-eclipse condition. It builds a vector-bundle open-hyperbolic framework and a local trace formula that links resonances of transfer operators to sums over periodic rays, leveraging symbolic dynamics on a suspended space to express dynamical thresholds as pressures $P(G)$ and $P(2G)$. The authors prove that each zeta function $\\eta_q$ has infinitely many poles in a rightward strip $\\Re s > \\beta$, with an analogous result for $\\eta_D$ when the boundary is real-analytic, and they identify $a_1 = P(G)$ and $b_1 = P(2G)$ as the critical abscissas governing convergence and resonance distribution. They further obtain density-type lower bounds for resonances akin to Naud's methods, revealing a deep connection between billiard dynamics, symbolic dynamics, and scattering resonances. These results provide insight into the spectral structure of multi-obstacle scattering and contribute to understanding potential essential spectral gaps in this geometric setting.
Abstract
We study the number of the poles of the meromorphic continuation of the dynamical zeta functions $η_N$ and $η_D$ for several strictly convex disjoint obstacles satisfying non-eclipse condition. We obtain a strip $\{z \in \mathbb C:\: {\rm Re}\: s > β\}$ with infinite number of poles. For $η_D$ we prove the same result assuming the boundary real analytic. Moreover, for $η_N$ we obtain a characterisation of $β$ by the pressure $P(2G)$ of some function $G$ on the space $Σ_A^f$ related to the dynamical characteristics of the obstacle.
