Statistical convex-cocompactness for mapping class groups of non-orientable surfaces

We show that a finite volume deformation retract \(\mathcal{T}_{\varepsilon_t}^{-}(\mathcal{N}_g)/\mathrm{MCG}(\mathcal{N}_g)\) of the moduli space \(\mathcal{M}(\mathcal{N}_g)\) of non-orientable surfaces \(\mathcal{N}_g\) behaves like the convex core of \(\mathcal{M}(\mathcal{N}_g)\), despite not...

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Veröffentlicht in:arXiv.org 2024-04
1. Verfasser: Khan, Sayantan
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Sprache:eng
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Zusammenfassung:We show that a finite volume deformation retract \(\mathcal{T}_{\varepsilon_t}^{-}(\mathcal{N}_g)/\mathrm{MCG}(\mathcal{N}_g)\) of the moduli space \(\mathcal{M}(\mathcal{N}_g)\) of non-orientable surfaces \(\mathcal{N}_g\) behaves like the convex core of \(\mathcal{M}(\mathcal{N}_g)\), despite not even being quasi-convex. We then show that geodesics in the convex core leave compact regions with exponentially low probabilities, showing that the action of \(\mathrm{MCG}(\mathcal{N}_g)\) on \(\mathcal{T}_{\varepsilon_t}^{-}(\mathcal{N}_g)\) is statistically convex-cocompact. Combined with results of Coulon and Yang, this shows that the growth rate of orbit points under the mapping class group action is purely exponential, pseudo-Anosov elements in mapping class groups of non-orientable surfaces are exponentially generic, and the action of mapping class group on the limit set in the horofunction boundary is ergodic with respect to the Patterson-Sullivan measure. A key step of our proof relies on complexity length, developed by Dowdall and Masur, which is an alternative notion of distance on Teichm\"uller space that accounts for geodesics that spend a considerable fraction of their time in the thin part.
ISSN:2331-8422