Figure 8:

Autocorrelation amplitude (solid curve) $A_{\Phi_{2s^2}}(t)= \vert \langle\Phi(\vec{r_1},\vec{r_2},t_0) \vert \Phi(\vec{r_1},\vec{r_2},t)\rangle \vert$. The dashed curve corresponds to an exponential fit. Other curves: analytic expansion from Eq.(27), for a different number p of functions included in the sum.