N. Chernov and R. Markarian
Dispersing billiards with cusps: slow decay of correlations
(622K, Postscript)

ABSTRACT.  Dispersing billiards introduced by Sinai are uniformly hyperbolic 
and have strong statistical properties (exponential decay of 
correlations and various limit theorems). However, if the billiard 
table has cusps (corner points with zero interior angles), then its 
hyperbolicity is nonuniform and statistical properties deteriorate. 
Until now only heuristic and experiments results existed predicting 
the decay of correlations as $\cO(1/n)$. We present a first rigorous 
analysis of correlations for dispersing billiards with cusps.