The superfluid transition of 4He in the presence of a heat current: renormalization-group theory

A review is given on the effect of a stationary heat current Q on the superfluid transition of 4He in the linear and nonlinear response regime. Results on various static and dynamic quantities as derived by the renormalization- group theory are discussed. This includes the temperature profile, the thermal bulk and boundary resistance, the interface between normal-liquid and superfluid 4He, the depression of Tλ, the superfluid density, second sound and the specific heat at finite Q.