Efimov Scenario for Overlapping Narrow Feshbach Resonances

While Efimov physics in ultracold atoms is usually modeled with an isolated Feshbach resonance many real world resonances appear in close vicinity to each other and are therefore overlapping. Here we derive a realistic model based on the mutual coupling of an open channel and two closed molecular channels while neglecting short-range physics as permitted by the narrow character of the considered resonances. The model is applied to three distinct scenarios with experimental relevance. We show that the effect of overlapping resonances is manifested most strongly at a narrow resonance in whose vicinity there is a slightly broader one. In this system the Efimov features are pushed to lower binding energies and smaller scattering lengths by a significant factor facilitating their experimental investigation. We also analyze the rich excitation spectrum of the system and construct its phase diagram.