Fig. \[spectra\] to construct bins $\Omega_i = \Delta {p_T}_i =
\left[p_{T_i},p_{T_{i+1}} \right]$ (left), or $\Omega_i = \Delta y_i =
\left[y_i,y_{i+1} \right]$ (right), as indicates by the drop-lines.

In section \[GCECE\] we calculate the multiplicity distributions $P(N_{\Omega})$ for arbitrary segments $\Omega$ for the ideal Boltzmann GCE and CE. To characterize the distribution one can calculate its (raw) moments $\langle N_{\Omega}^n \rangle$ from: $$\label{Moments}
\langle N_{\Omega}^n \rangle ~=~ \sum \limits_{N_{\Omega}=0}^{\infty}
~N_{\Omega}^n~ P \left(N_{\Omega} \right)~.$$ A convenient measure for the width of a distribution is the scaled variance: $$\label{ScaledVar} 
\omega_{\Omega} ~\equiv~ \frac{\langle N_{\Omega}^2 \rangle - \langle N_{\Omega}
  \rangle^2}{\langle N_{\Omega} \rangle} ~.$$ In order to remove simple scaling effects, the bin sizes or segments are chosen such that each bin or segment contains the same fraction $q= \langle
N_{\Omega} \rangle ~/~ \langle N_{4\pi} \rangle$ of the total yield (compare Eq.(\[ScaledVar\])). Here $\langle N_{\Omega} \rangle$ denotes the average particle number in the momentum space segment $\Omega$, and $\langle N_{4\pi}
\rangle$ denotes the average total ($4\pi$ integrated) multiplicity. The effect of finite acceptance can approximately be taken into account by [@CEfluc1]: $$\label{accscaling}
\omega_{q} ~=~ 1 + q \left(\omega_{4\pi}-1 \right)~,$$ where $\omega_{4\pi}$ assumes the ideal situation when all particles are detected, while $\omega_{q}$ assumes that particles are 