Slow down of the electronic relaxation close to the Mott transition

We investigate the time-dependent reformation of the quasiparticle peak in a correlated metal near the Mott transition, after the system is quenched into a hot electron state and equilibrates with an environment which is colder than the Fermi-liquid crossover temperature. Close to the transition, we identify a purely electronic bottleneck timescale, which depends on the spectral weight around the Fermi energy in the bad metallic phase in a non-linear way. This timescale can be orders of magnitude larger than the bare electronic hopping time, so that a separation electronic and lattice timescales may break down. The results are obtained using nonequilibrium dynamical mean-field theory and a slave-rotor representation of the Anderson impurity model.