  We assess the importance of tidal evolution and its interplay with magnetic
braking in the population of hot-Jupiter planetary systems. By minimizing the
total mechanical energy of a given system under the constraint of stellar
angular momentum loss, we rigorously find the conditions for the existence of
dynamical equilibrium states. We estimate their duration, in particular when
the wind torque spinning down the star is almost compensated by the tidal
torque spinning it up. We introduce dimensionless variables to characterize the
tidal evolution of observed hot Jupiter systems and discuss their spin and
orbital states using generalized Darwin diagrams based on our new approach. We
show that their orbital properties are related to the effective temperature of
their host stars. The long-term evolution of planets orbiting F- and G-type
stars is significantly different owing to the combined effect of magnetic
braking and tidal dissipation. The existence of a quasi-stationary state, in
the case of short-period planets, can significantly delay their tidal evolution
that would otherwise bring the planet to fall into its host star. Most of the
planets known to orbit F-type stars are presently found to be near this
stationary state, probably in a configuration not too far from that they had
when their host star settled on the zero-age main sequence. Considering the
importance of angular momentum loss in the early stages of stellar evolution,
our results indicate that it has to be taken into account also to properly test
the migration scenarios of planetary system formation.
