This paper presents a short overview of event-by-event correlations and fluctuations analysis with strongly intensive quantities measured by ALICE at LHC in pp, p--Pb, Xe--Xe, and Pb--Pb collisions in the overall energy regime ranging from √sNN=0.9 up to 13~TeV.
The evolution of the forward-backward strongly intensive quantity Σ is analyzed as a function of the distance between forward and backward pseudorapidity intervals (η gap), the centrality of the collision, and the width of the centrality bin. The observable is studied by means of different centrality estimators. The net-charge fluctuations with νdyn[+,−], are examined as a function of charged-particle density (dNch/dη).
Our study demonstrates that Σ indeed exhibits the properties of a strongly intensive quantity in terms of the independent source models, providing information on the early collision dynamics which is far more direct than that obtained from bn−ncorr.
The measured negative values of νdyn[+,−] indicate the dominance of the correlation between oppositely charged particles. A smooth evolution of net-charge fluctuations is observed from small to large collision systems.
