  We study a heavy-heavy-light three-body system confined to one space
dimension provided the binding energy of an excited state in the heavy-light
subsystems approaches zero. The associated two-body resonance is characterized
by (i) the structure of the weakly bound excited heavy-light state and (ii) the
presence of deeply bound heavy-light states. The consequences of these aspects
for the behavior of the three-body system are analyzed. We find strong
indication for universal behavior of both three-body binding energies and wave
functions close to different excited-state resonances in the heavy-light
subsystems.
