Symmetric cumulants, the novel flow observables which quantify the correlations between event-by-event fluctuations of two different flow harmonics, have been utilized extensively by the experimentalists in recent flow analyses in ultra-relativistic nuclear collisions, both at RHIC and LHC.
These observables provide the strong constraints for the details of QGP's temperature dependence of \eta/s, which is currently heavily studied by the theorists, and to which the individual flow harmonics are nearly insensitive. In addition, symmetric cumulants have a potential to disentangle for the first time the two contributions to anisotropic flow stemming from initial conditions and from the transport properties of the QGP. This in turn could enable the theorists to perform independent modelling and tuning of initial configurations of nuclear collisions and of the system properties of the produced QGP.
In this talk the overview of experimental results collected so far for symmetric cumulants, over a wide range of different collision systems and colliding energies, will be presented. The possibility how to generalize these observables to extract even further independent constrains on initial conditions and QGP properties will be discussed at the end.