Positive crossratios, barycenters, trees and applications to maximal representations

  • Marc Burger

    ETH Zürich, Switzerland
  • Alessandra Iozzi

    ETH Zürich, Switzerland
  • Anne Parreau

    Université Grenoble Alpes, France
  • Maria Beatrice Pozzetti

    Heidelberg University, Germany
Positive crossratios, barycenters, trees and applications to maximal representations cover
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Abstract

We study metric properties of maximal framed representations of fundamental groups of surfaces in symplectic groups over real closed fields, interpreted as actions on Bruhat–Tits buildings endowed with adapted Finsler norms. We prove that the translation length can be computed as intersection with a geodesic current, give sufficient conditions guaranteeing that such a current is a multicurve, and, if the current is a measured lamination, construct an isometric embedding of the associated tree in the building. These results are obtained as application of more general results of independent interest on positive crossratios and actions with compatible barycenters.

Cite this article

Marc Burger, Alessandra Iozzi, Anne Parreau, Maria Beatrice Pozzetti, Positive crossratios, barycenters, trees and applications to maximal representations. Groups Geom. Dyn. 18 (2024), no. 3, pp. 799–847

DOI 10.4171/GGD/767