  Our first very wide survey of the supercritical phase diagram and its key
properties reveals a universal interrelation between dynamics and
thermodynamics and an unambiguous transition between liquidlike and gaslike
states. This is seen in the master plot showing a collapse of the data
representing the dependence of specific heat on key dynamical parameters in the
system for many different paths on the phase diagram. As a result, the observed
transition is path-independent. We call it a "c"-transition due to the
"c"-shaped curve parameterizing the dependence of the specific heat on key
dynamical parameters. The "c"-transition has a fixed inversion point and
provides a new structure to the phase diagram, operating deep in the
supercritical state (up to at least 2000 times the critical pressure and 50
times the critical temperature). The data collapse and path independence as
well as the existence of a special inversion point on the phase diagram are
indicative of either of a sharp crossover or a new phase transition in the
deeply supercritical state.
