Effect of electron-electron interactions on the average polarizability of a mesoscopic system

A comparison between an analytical calculation of the polarizability of a mesoscopic interacting system in the random-phase approximation and numerical exact diagonalization results is presented. While for weak interactions the analytical calculation fits the numerical results rather well, deviations appear for stronger interactions. This is the result of the appearance of intermediate-range correlations in the electron density, which suppresses the polarizability below its classical value. The relevance to quantum-dot systems is discussed.