Two Interacting Quasiparticles Above the Fermi Sea

We study numerically the interaction and disorder effects for two quasiparticles in two and three dimensions. The dependence of the interaction-induced Breit-Wigner width $\gamma$ on the excitation energy above the Fermi level $\left(\epsilon \right)$, the disorder strength, and the system size are determined. A regime is found where $\gamma$ is practically independent of $\epsilon$. The results allow us to estimate the two quasiparticle mobility edge.