Energy-momentum conservation and Lipkin's zilch
  As Noether's theorem states any differentiable symmetry of the action of a physical system has a corresponding conservation law. Lipkin introduced the conservation laws of zilches. But the corresponding symmetries are yet to be determined. Here we find a method to determine those symmetries and by direct calculations express the zilch tensor's relation to current-density for $n$-dimensional Minkowski space-time. Also, we extend this method to calculate symmetries of conservation of energy-momentum. Finally we show that in the special case of n=4, our general equation governing optical chirality reduces to the continuity equation of optical chirality density and optical chirality flow. 
H. Lashkari-Ghouchani, M.H. Alizadeh
physics.optics math-ph math.MP