Degenerations of k-positive surface group representations

Abstract

We introduce \emph{k-positive representations}, a large class of $\{1,\dots ,k\}$--Anosov surface group representations into PGL(E) that share many features with Hitchin representations, and we study their degenerations: unless they are Hitchin, they can be deformed to non-discrete representations, but any limit is at least (k-3)-positive and irreducible limits are (k-1)-positive. A major ingredient, of independent interest, is a general limit theorem for positively ratioed representations.

39 pages, 4 figues. Comments welcome! v2: incorporated referee comments, improved exposition. To appear in J. Top