| In multi-dimensional barrier tunneling, there coexist different semiclassical mechanisms, traditional instanton and stable-unstable manifold guided tunneling found recently, which make different forms of tunneling spectra, a localized spectrum and widely spread plateau, respectively. In this talk, we study how the change of mechanism occurs with change of perturbation strength and give a criterion to judge which mechanism is dominant for a given set of parameters, together with a simple method to calculate tunneling rates of both mechanisms. |
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