Critical phenomena in disc-percolation model and its application to relativistic heavy ion collisions

Through studying the critical phenomena in continuum-percolation of discs, we find a new approach to locate the critical point, i.e. using the inflection point of $P_\infty$ as an evaluation of the percolation threshold. The susceptibility, defined as the derivative of $P_\infty$, possess finite-size scaling property, where the scaling exponent is the reciprocal of $\nu$ -- the critical exponent of correlation length. The possible application of this approach to the study of the critical phenomena in relativistic heavy ion collisions is discussed. The critical point for deconfinement can be extracted by the inflection point of $P_{\rm QGP}$ -- the probability for the event with QGP formation. The finite-size scaling of its derivative can give the critical exponent $\nu$, which is a rare case that can provide an experimental measure of a critical exponent in heavy ion collisions.