We report a resonant inelastic x-ray scattering study of charge excitations in the quasi-one-dimensional Mott insulator . We observe a continuum of low-energy excitations, the onset of which exhibits a small dispersion of . Within this continuum, a highly dispersive feature with a large sinusoidal dispersion () is observed. We have also measured the optical conductivity, and studied the dynamic response of the extended Hubbard model with realistic parameters, using a dynamical density-matrix renormalization group method. In contrast to earlier work, we do not find a long-lived exciton, but rather these results suggest that the excitation spectrum comprises a holon-antiholon continuum together with a broad resonance.
- Received 21 July 2003
- Published 2 April 2004
© 2004 The American Physical Society