News on mean pion multiplicity from NA61/SHINE

Abstract

NA61/SHINE is a large acceptance fixed target experiment at the CERN SPS which studies final hadronic states in interactions between various particles and nuclei. The main topic of this contribution are preliminary results for mean negatively charged pion multiplicities $\langle \pi^{-} \rangle$ from central Ar+Sc and Be+Be collisions. The data were taken recently by the NA61/SHINE collaboration for a wide range of beam momenta. Measured rapidity distributions $\frac{dn}{dy}$ were extrapolated to unmeasured regions to obtain total multiplicities $\langle \pi^{-} \rangle$. A new scheme to calculate the mean number of wounded nucleons $\langle W \rangle$ utilizing the EPOS MC model is described. Using data from other experiments, a comparison of $\frac{\langle \pi \rangle}{\langle W \rangle}$ for different collisions and beam momenta is discussed