The key feature of an orbital wave or orbiton is a significant dispersion,
which arises from exchange interactions between orbitals on distinct sites. We
study the effect of a coupling between orbitons and phonons in one dimension
using continuous unitary transformations (CUTs). Already for intermediate
values of the coupling, the orbiton band width is strongly reduced and the
spectral density is dominated by an orbiton-phonon continuum. However, we find
sharp features within the continuum and an orbiton-phonon anti-bound state
above. Both show a significant dispersion and should be observable
experimentally.Comment: 7 pages, 7 figures; strongly enlarged, comprehensive revised version
according to the referees' suggestions, in pres
