Recently, two strongly intensive quantities, $\Delta [A,B]$ and $\Sigma [A,B]$, designed for the study of event-by-event fluctuations in high-energy collisions were introduced. They are defined in terms of two extensive event observables $A$ and $B$. In this paper a special normalization of the $\Delta [A,B]$ and $\Sigma [A,B]$ fluctuation measures is proposed. It ensures that they are dimensionless and yields a common scale required for a quantitative comparison of fluctuations of different, in general dimensional, extensive quantities. Namely, the properly normalized strongly intensive measures assume the value one for fluctuations given by the independent particle model, and they are equal to zero when the $A$ and $B$ observables have constant values in all collision events.

• Received 20 March 2013

DOI:https://doi.org/10.1103/PhysRevC.88.024907