Optimal decay rate for the wave equation on a square with constant   damping on a strip
  We consider the damped wave equation with Dirichlet boundary conditions on the unit square. We assume the damping to be a characteristic function of a strip. We prove the exact $t^{-4/3}$-decay rate for the energy of classical solutions. This answers a question of Anantharaman and L\'eautaud (2014). 
Reinhard Stahn
math-ph math.AP math.MP