date:UNIV NACL AUTONOMA MEXICO,INST FIS,01000 MEXICO CITY,DF,MEXICO
We study the three-phase contact line L and its tension tau near the interfacial phase transition from partial to complete wetting. We analyse the singularity of tau at first-order wetting transitions and show that it displays the universal features of a critical endpoint. These are most notably represented by novel amplitude ratios for tau, but also, this identification explains the extreme spatial extent and asymmetry of the line inhomogeneity. We determine universal amplitude ratios for both short-range and long-range forces from an interface displacement model. We focus on the mean-field regime, valid for three-dimensional van der Waals systems.