Effect of electron–phonon coupling on spin–charge separation in one-dimensional strongly correlated electron systems

Abstract We examine the single-particle excitation spectrum in the one-dimensional Hubbard–Holstein model at half-filling by performing the dynamical density matrix renormalization group calculation. We find that the spin–charge separation is robust against the electron–phonon coupling, although both of the spinon and holon branches are affected by phonons. We propose an effective model for the spectrum that is defined by a superposition of spectra for the Holstein model.