English

Algebraic intersection in regular polygons

Dynamical Systems 2024-11-25 v2 Differential Geometry

Abstract

We study the function \mboxKVol:(X,ω)\mboxVol(X,ω)supα,β\mboxInt(α,β)lg(α)lg(β)\mbox{KVol} : (X,\omega)\mapsto \mbox{Vol} (X,\omega) \sup_{\alpha,\beta} \frac{\mbox{Int} (\alpha,\beta)}{l_g (\alpha) l_g (\beta)} defined on the moduli spaces of translation surfaces. More precisely, let Tn\mathcal T_n be the Teichm\"uller discs of the original Veech surface (Xn,ωn)(X_n,\omega_n) arising from right-angled triangle with angles (π/2,π/n,(n2)π/2n)(\pi/2,\pi/n,(n-2)\pi/2n) by the unfolding construction for n5n\geq 5. For n1mod2n \equiv 1 \mod 2 and any (X,ω)Tn(X,\omega)\in \mathcal T_n, we establish the (sharp) bounds n2cotπn\mboxKVol(X,ω)n2cotπn1sin2πn. \frac{n}{2} \cot \frac{\pi}{n} \leq \mbox{KVol}(X,\omega) \leq \frac{n}{2} \cot \frac{\pi}{n} \cdot \frac1{\sin \frac{2\pi}{n}}. The lower bound is uniquely realized at (Xn,ωn)(X_n,\omega_n).

Keywords

Cite

@article{arxiv.2110.14235,
  title  = {Algebraic intersection in regular polygons},
  author = {Julien Boulanger and Erwan Lanneau and Daniel Massart},
  journal= {arXiv preprint arXiv:2110.14235},
  year   = {2024}
}

Comments

New version with the first author added and completely different methods. We focus on the $n=2m+1$ case, the $n=4m$ case is dealt with in a forthcoming paper by the first author. 30pages, 15 figures

R2 v1 2026-06-24T07:13:28.317Z