Topological groups of Kac-Moody type, Fuchsian twinnings and their   lattices
  This paper deals with a class of totally disconnected groups acting on buildings, among which are certain Kac-Moody groups. The apartments of our buildings are hyperbolic planes tiled by right-angled polygons. We discuss linearity properties for the groups, as well as an analogy with semisimple groups over local fields of positive characteristic. Looking for counter-examples to this analogy leads to the construction of Moufang twinnings "with several ground fields". 
Bertrand Remy (Universite de Grenoble 1), Mark Ronan (University of   Illinois at Chicago)