| We study level-spacing statistics for systems with a mixed phase space, in which regions of regular and chaotic dynamics coexist. Assuming statistical independence of the corresponding subspectra, spacings are described by the Berry-Robnik distribution. However, due to dynamical tunneling, regular and chaotic states are coupled. This leads to small avoided crossings which vary in size over many orders of magnitude, depending on the regular state involved. We demonstrate that this implies a power law of the level-spacing distribution for small spacings. It is analytically and numerically shown that the power-law exponent semiclassically scales linearly with the effective Planck constant. |
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