Spectral properties of a partially spin-polarized one-dimensional Hubbard/Luttinger superfluid

We calculate the excitation spectra of a spin-polarized Hubbard chain away from half filling using a high-precision momentum-resolved time-dependent density-matrix renormalization-group method. Focusing on the U<0 case, we present in some detail the single-fermion, pair, density, and spin spectra and discuss how spin-charge separation is altered for this system. The pair spectra show a quasicondensate at a nonzero momentum proportional to the polarization, as expected for this Fulde-Ferrell-Larkin-Ovchinnikov-type superfluid.