Multiplicity and forward energy fluctuations from the NA61/SHINE experiment CERN

Preliminary results for multiplicity and forward energy fluctuations are presented for inelastic p+p and the most central $^7$Be $+ \ ^9$Be and $^{40}$Ar $+ \ ^{45}$Sc collisions. The data were obtained by the NA61/SHINE detector at the CERN SPS. Centrality selection and forward energy measurement are based on the nucleon spectator energy in the forward hemisphere determined by the projectile spectator detector. The scaled variance $\omega$ of the multiplicity distribution and the strongly intensive quantity $\Omega$ of multiplicity and forward energy fluctuations were calculated for negatively charged hadrons. The scaled variance changes little when going from p+p to Be+Be collisions and drops dramatically from Be+Be to Ar+Sc interactions. A comparison with the EPOS event generator is shown.