Dressed (Renormalized) Coordinates in a Nonlinear System
  In previous publications dressed coordinates and dressed states has been introduced. Specifically, a system composed by a harmonic oscillator interacting linearly with an infinity set of other oscillators has been treated. In this paper we show how to generalize such dressed coordinates and dressed states to a nonlinear version of this system. Also we clarify some misunderstandings about the concept of dressed coordinates. Indeed now we prefer to call them renormalized coordinates to emphasize the analogy with the renormalized fields in quantum field theory. 
G. Flores Hidalgo and Y. W. Milla