Quasiparticle and phonon lifetimes in superconductors

Low-energy quasiparticle scattering, recombination, and branch-mixing lifetimes and phonon pair-breaking and scattering lifetimes are calculated for superconductors. The quasiparticle calculations relate these lifetimes to the low-frequency behavior of α2(Ω) F (Ω). Results are obtained using the low-frequency approximate form α2(Ω) F (Ω) = bΩ2, with b determined from electron tunneling measurements. For the strong-coupling superconductors Pb and Hg, the full tunneling form for α2(Ω) F (Ω) is used. The phonon lifetimes are shown to depend on α2(Ω). Results are compared with experiment