Escape from a circle and Riemann hypotheses
  We consider open circular billiards with one and with two holes. The exact formulas for escape are obtained which involve the Riemann zeta function and Dirichlet L-functions. It is shown that the problem of finding the exact asymptotics in the small hole limit for escape in some of these billiards is equivalent to the Riemann hypothesis. 
Leonid A. Bunimovich (Georgia Tech) and Carl P. Dettmann (Bristol)