Equidistribution of saddle connections on translation surfaces

Abstract

Fix a translation surface $X$, and consider the measures on $X$ coming from averaging the uniform measures on all the saddle connections of length at most $R$. Then as $R\to\infty$, the weak limit of these measures exists and is equal to the Lebesgue measure on $X$. We also show that any weak limit of a subsequence of the counting measures on $S^1$ given by the angles of all saddle connections of length at most $R_n$, as $R_n\to\infty$, is in the Lebesgue measure class. The proof of the first result uses the second result, together with the result of Kerckhoff-Masur-Smillie that the directional flow on a surface is uniquely ergodic in almost every direction.Comment: 25 pages, 4 figures. Strengthened Theorem 1.5, lower bound for saddle connections in a sector, so that constant is independent of surface. New proof of this result. This is the final version. To appear in Journal of Modern Dynamic