  Motivated by the observation of localized traveling-wave states (`pulses') in
convection in binary liquid mixtures, the interaction of fronts is investigated
in a real Ginzburg-Landau equation which is coupled to a mean field. In that
system the Ginzburg-Landau equation describes the traveling-wave amplitude and
the mean field corrsponds to a concentration mode which arises due to the
slowness of mass diffusion. For single fronts the mean field can lead to a
hysteretic transition between slow and fast fronts. Its contribution to the
interaction between fronts can be attractive as well as repulsive and depends
strongly on their direction of propagation. Thus, the concentration mode leads
to a new localization mechanism, which does not require any dispersion in
contrast to that operating in the nonlinear Schr\"odinger equation. Based on
this mechanism alone, pairs of fronts in binary-mixture convection are expected
to form {\it stable} pulses if they travel {\it backward}, i.e. opposite to the
phase velocity. For positive velocities the interaction becomes attractive and
destabilizes the pulses. These results are in qualitative agreement with recent
experiments. Since the new mechanism is very robust it is expected to be
relevant in other systems as well in which a wave is coupled to a mean field.
