EFFECTIVE MASS OF QUASI-PARTICLES IN A T-J MODEL WITH ELECTRON-PHONON INTERACTIONS

The change of the spectral properties of the single-particle Green's function due to a coupling to optical phonons is investigated for strongly correlated electrons. The phonon-induced mass renormalization of the carriers that propagate in the t-J model on scale J is much larger than in the corresponding uncorrelated model, except in the limit of J --> 0 where the weight of the quasiparticle pole tends to zero. The enhancement is a consequence of the slow coherent motion of the spin polarons, which makes electron-phonon interactions more effective. Two scaling laws are determined which relate the mass renormalization to phonon frequency and coupling constant.