Statics and dynamics of charge fluctuations in the t-J model.

The equation for the charge vertex γ of the t−J model is derived and solved in leading order of an 1/N expansion, working directly in terms of Hubbard operators. Various quantities which depend crucially on γ are then calculated, such as the life time and the transport life time of electrons due to a charge coupling to other degrees of freedom and the charge-charge correlation function. Our results show that the static screening of charges and the dynamics of charge fluctuations depend only weakly on J and are mainly determined by the constraint of having no double occupancies of sites. PACS numbers: 72.12.Di, 63.20.Kr., 74.72.-h