Quasiparticle inelastic lifetimes in disordered superconducting films

We present a comprehensive theory of quasiparticle inelastic lifetimes close to equilibrium in disordered superconducting films. The lifetime due to Coulomb interactions in two-dimensional (2D) films is calculated in analogy to a recent 3D calculation. For the phonon contribution, we extend the results of Reizer and Sergeyev for clean 3D systems to 2D, and determine the leading disorder renormalization. We then construct an interpolation formula for films of finite thickness that correctly reproduces the 2D and 3D limits. We give a general discussion of our results, and compare them with experiments. Agreement with measurements on thick films is good, while in the 2D limit nonequilibrium effects are likely to play an important role.