The collective field theory (see nLab for a lits of main historical references) which came up as a generalization of the Bohm-Pines method in treating plasma oscillations is often used in the study of large N asymptotics (e.g. of matrix models). I have seen few cases where the equations for collective field are derived; the equations are obtained using approximations and look more systematically understood by other methods than those available at dawn of collective field theory (i.e. since the works of Sakita and Jevicki).
Are there now systematic methods to derive collective field theory equations to any order in 1/N ? Also if the Yaffe's methods concerning coherent state methods in large N asymptotics are ever used in collective field theory ? The subject looks interesting for doing some work (I have some background in coherent state techniques), but I do not know where the current state of the art is.
EDIT: added a bounty to renew interest.
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