The Interplay of Spin and Charge Channels in Zero Dimensional Systems

We study the interplay of charge and spin (zero-mode) channels in quantum dots. The latter affects the former in the form of a distinct signature on the differential conductance. We also obtain both longitudinal and transverse spin susceptibilities. All these observables, underlain by spin fluctuations, become accentuated as one approaches the Stoner instability. The non-perturbative effects of zero-mode interaction are described in terms of the propagation of gauge bosons associated with charge (U(1)) and spin (SU(2)) fluctuations in the dot, while transverse spin fluctuations are analyzed perturbatively.