  In solid state physics, any symmetry breaking is known to be associated with
emergence of an order parameter. However, the order parameter for molecular and
crystal chirality, which is a consequence of parity and mirror symmetry
breaking, has not been known since its discovery. In this article, the authors
show that the order parameter for chirality can be defined by electric toroidal
monopole G_0. By this definition, one becomes able to discuss external filed
that can distinguish two different enantiomers only by physical fields. In
addition, dynamics and fluctuations of the order parameter G_0 can be
discussed, with which one can obtain fruitful insights on a spin filtering
effect called CISS (Chirality Induced Spin Selectivity). Emergence of
time-reversal-odd dipole M_z by time propagation of G_0 quantities is discussed
to explain the enantioselective effect (chiral resolution) at a ferromagnetic
surface.
