Phase-space dependence of particle-ratio fluctuations in Pb+Pb collisions from 20A to 158A GeV beam energy

Understand

A novel approach, the identity method, was used for particle identification and the study of fluctuations of particle yield ratios in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS).

• This procedure allows to unfold the moments of the unknown multiplicity distributions of protons (p), kaons (K), pions ($\pi$) and electrons (e).
• Using these moments the excitation function of the fluctuation measure $\nu_{\text{\text{dyn}}}$[A,B] was measured, with A and B denoting different particle types.
• The obtained energy dependence of $\nu_{\text{dyn}}$ agrees with previously published NA49 results on the related measure $\sigma_{\text{dyn}}$.