Surface Free Energy of Hadronic and Gluonic Droplets From Lattice QCD

We present the results of a computation of the surface tension on hadronic and gluonic droplets in finite temperature quenched lattice QCD. The surface free energy was obtained by integrating the average action along a path in coupling space corresponding to growing and melting a spherical droplet of a given radius. So far droplets of radius 4, 5 and 8 (in lattice units) have been considered. After discussing ambiguities in the definition of the surface tension due to a droplet’s finite size and thick interface, we compare our results with the Bag model study of Mardor and Svetitsky. Our calculations appear to confirm qualitatively their prediction of a negative surface tension for hadronic droplets with small radii. A similar result is found for gluonic droplets, in contrast however with the Bag model. We also compare our results with the recent lattice simulation of Kajantie, Karkkainen and Rummukainen.