Two-loop approximation in the Coulomb blockade problem
Abstract
We study Coulomb blockade (CB) oscillations in the thermodynamics of a metallic grain which is connected to a lead by a tunneling contact with a large conductance g_0 in a wide temperature range, E_Cg_0^4 e^{-g_0/2}<T<E_C, where E_C is the charging energy. Using the instanton analysis and the renormalization group we obtain the temperature dependence of the amplitude of CB oscillations which differs from the previously obtained results. Assuming that at T < E_Cg_0^4 e^{-g_0/2} the oscillation amplitude weakly depends on temperature we estimate the magnitude of CB oscillations in the ground state energy as E_Cg_0^4 e^{-g_0/2}.