Particle-Hole Excitations and Self Energy of Quasi-Particles in a Fermi Liquid

Abstract

The experimental fact¹ that some low-temperature properties of He³, notably the specific heat and thermal conductivity, deviate from the lowest-order temperature behaviour predicted by Landau,² even below 20 m°K has given rise to several theoretical investigations.³ Estimates of the temperature range in which the lowest-order Landau terms should give an accurate description, based on dimensional arguments, indicate a range of about 0–5°K. This may seem to be a failure of Landau’s theory. But such a conclusion is warranted only if the quantity in question has a power series expansion at low temperatures. As we shall see this is not the case, as indeed the term following the linear term in the specific heat, for example, is T ³ ln T which rules out the dimensional considerations.