Kinetic equation with exact charge conservation
  We formulate the kinetic master equation describing the production of charged particles which are created or destroyed only in pairs due to the conservation of their Abelian charge.Our equation applies to arbitrary particle multiplicities and reproduces the equilibrium results for both canonical (rare particles) and grand canonical (abundant particles) systems. For canonical systems, the equilibrium multiplicity is much lower and the relaxation time is much shorter than the naive extrapolation from the grand canonical ensemble results. Implications for particle chemical equilibration in heavy-ion collisions are discussed. 
C.M. Ko, V. Koch, Zi-wei Lin, K. Redlich, M. Stephanov and Xin-Nian   Wang