Approximation theory 4 Closed-time-path (CTP) 4 Quantum theory 4 ACCION DE INFLUENCIA 3 CAMINO TEMPORAL CERRADO 3 CLOSED TIME PATH 3 ECUACION KPZ 3 ECUACIONES DIFERENCIALES ESTOCASTICAS 3 GRUPO DE RENORMALIZACION WILSONIANO 3 INFLACION 3 INFLATION 3 INFLUENCE ACTION 3 KPZ EQUATION 3 LAMBDA PHI4 THEORY 3 NONEQUILIBRIUM QUANTUM FIELD THEORY 3 STOCHASTIC DIFFERENTIAL EQUATIONS 3 TEORIA CUANTICA DE CAMPOS FUERA DEL EQUILIBRIO 3 TEORIA LAMBDA PHI4 3 WILSONIAN RENORMALIZATION GROUP 3 Arbitrary orders 2 Atoms 2 Bethe-salpeter equations 2 Bose-Einstein condensate 2 Bose-Einstein condensates 2 Closed time paths 2 Coarse-grained 2 Condensation 2 Correlation methods 2 Current fluctuations 2 Driven systems 2