Interaction corrections at intermediate temperatures: Dephasing time

We calculate the temperature dependence of the weak-localization correction in a two-dimensional system at arbitrary relation between temperature T and the elastic mean free time. We describe the crossover in the dephasing time ${\tau }_{\phi }\mathrm{}\left(T\right)\mathrm{}$ between the high-temperature, $1/{\tau }_{\phi }\simeq T^2\ln T,$ and the low-temperature $1/{\tau }_{\phi }\simeq T$ behaviors. The prefactors in these dependences are not universal, but are determined by the Fermi-liquid constant characterizing the spin exchange interaction.