Two overlapping resonances in a flat continuum

Turning now to the case of a flat continuum (constant 8), we can readily construct the case of two overlapping resonances, in which case the phase shift has a resonant part 

Such formulae are used to analyse cases in which two Beutler-Fano resonances overlap in energy. For resonances originating from two different channels, different values of q (qi and qf) are introduced in (8.39) (see, e.g., Heinzmann et al. [427]). Such situations are also treated by MQDT [428, 429] 

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