Nonlocal form of quantum off-shell kinetic equation

A new nonlocal form of the off-shell kinetic equation is derived. While being equivalent to the Kadanoff-Baym and Botermans-Malfliet formulations in the range of formal applicability, it has certain advantages beyond this range. It possessesmore accurate conservation laws for Noether quantities than those in the Botermans-Malfliet formulation. At the same time the nonlocal form, similarly to the Botermans-Malfliet one, allows application of the test-particle method for its numerical solution, which makes it practical for simulations of heavy-ion collisions. The physical meaning of the time-space nonlocality is clarified.