  Understanding electronic properties that violate the Landau Fermi liquid
paradigm in cuprate superconductors remains a major challenge in condensed
matter physics. The strange metal state in overdoped cuprates that exhibits
linear-in-temperature scattering rate and dc resistivity is a particularly
puzzling example. Here, we compute the electronic scattering rate in the
two-dimensional Hubbard model using cluster generalization of dynamical
mean-field theory. We present a global phase diagram documenting an apparent
non-Fermi liquid phase, in between the pseudogap and Fermi liquid phase in the
doped Mott insulator regime. We discover that in this non-Fermi liquid phase,
the electronic scattering rate $\gamma_k(T)$ can display linear temperature
dependence as temperature $T$ goes to zero. In the temperature range that we
can access, the $T-$ dependent scattering rate is isotropic on the Fermi
surface, in agreement with recent experiments. Using fluctuation diagnostic
techniques, we identify antiferromagnetic fluctuations as the physical origin
of the $T-$ linear electronic scattering rate.
