  The multiplicity per rapidity of the well-identified particles $\pi^{-}$,
$\pi^{+}$, $k^{-}$, $k^{+}$, $\bar{p}$, $p$, and $p-\bar{p}$ measured in
different high-energy experiments, at energies ranging from $6.3$ to
$5500~$GeV, are successfully compared with the Cosmic Ray Monte Carlo (CRMC)
event generator. For these rapidity distributions, we introduce a theoretical
approach based on fluctuations and correlations (Carruthers) and another one
based on statistical thermal assumptions (hadron resonance gas model). Both
approaches are fitted to the two sets of results deduced from experiments and
simulations. We found that the Carruthers approach reproduces well the full
range of multiplicity per rapidity for all produced particles, at the various
energies, while the HRG approach fairly describes the results within a narrower
rapidity-range. While the Carruthers approach seems to match well with the
Gaussian normal distribution, ingredients such as flow and interactions should
be first incorporated in the HRG approach.
