About common physical nature of divergence and interference

The difference of actions between nearly lying unstable 8'' and 0’’ like trajectories in two dimensions is computed by methods of chaotic dynamics. We found it to be equal to $pY\mathrm{\Theta }\mathrm{/}2$, where $\mathrm{\Theta }$ is angle between paths at cross, $Y$ is distance between paths, and $p$ is momentum. This kind of periodic trajectories contributes ${\tau }^2$ (interference) term to spectral form-factor.