  Excited conduction electrons, conduction holes, and valence holes in
monolayer electron-doped graphene exhibit unusual Coulomb decay rates. The
deexcitation processes are studied using the screened exchange energy. They
might utilize the intraband single-particle excitations (SPEs), the interband
SPEs, and the plasmon modes, depending on the quasiparticle states and the
Fermi energies. The low-lying valence holes can decay through the undamped
acoustic plasmon, so that they present very fast Coulomb deexcitations,
nonmonotonous energy dependence, and anisotropic behavior. However, the
low-energy conduction electrons and holes are similar to those in a
two-dimensional electron gas. The higher-energy conduction states and the
deeper-energy valence ones behave similarly in the available deexcitation
channels and have a similar dependence of decay rate on the wave vector ${\bf
k}$.
