  We study the time evolution of the Hubbard model driven by a half-cycle or
monocycle pulsed electric field F(t) using the nonequilibrium dynamical
mean-field theory. We find that for properly chosen pulse shapes the
electron-electron interaction can be effectively and permanently switched from
repulsive to attractive if there is no energy dissipation. The physics behind
the interaction conversion is a nonadiabatic shift $\delta$ of the population
in momentum space. When $\delta\sim\pi$, the shifted population relaxes to a
negative-temperature state, which leads to the interaction switching. Due to
electron correlation effects $\delta$ deviates from the dynamical phase
$\phi=\int dt F(t)$, which enables the seemingly counterintuitive
repulsion-to-attraction transition by a monocycle pulse with $\phi=0$.
