HEAVY PARTICLES IN METALS - A FERMI-SURFACE EFFECT.

A heavy particle interacting with degenerate Fermi systems is investigated theoretically. Main concern is on mass shift and vertex corrections. The particle may be a free particle or a Bloch particle. The temperature may be higher than a characteristic temperature or lower than it. These corrections are expanded in a power of the interaction and found to involve logarithms of the temperature or of the mass ratio. Only the highest power of the logarithms is retained in a given order of the expansion. The following results are obtained. The mass correction is non-existent for a free particle, whereas the mass is enhanced for a Bloch particle. The enhancement is proportional to a power of the temperature at higher temperatures, but is a constant at lower temperatures. The vertex correction exists for both types of the particle. It is also proportional to a power of the temperature and tends to a constant towards lower temperatures. Three real systems, protons in transition metals, d-electrons in transition metals and negative ions in liquid **3He, are considered in the light of these results.