Comparison of field variables for critical phenomena description

We report the findings of the reanalysis of critical phenomena which occur in three different multicomponent systems found in the literature. Multicomponent systems allow for the description of critical phenomena in terms of more than one field variable as the critical curve is approached in the multidimensional phase space. We show empirically that one field variable provides the most relevant description of the critical phenomena over all the others. This relevant field variable displays universality in both the critical exponents and amplitudes. The key feature of this relevant field variable is that its variation toward the critical curve is along paths that are never tangent to the critical curve.