Speaker
Description
We have constructed a gauge-invariant measure for deconfinement based on the percolation of electric center fluxes in full lattice QCD, to describe the associated geometric phase transition without a thermodynamic singularity. Our percolation measure reduces to 't Hooft's electric fluxes for the Z_N center-symmetry transition in the pure SU(N) gauge theory. In the corresponding Z_N-spin models, this percolation phase transition persists with explicit symmetry breaking into the crossover region along the Kertesz line, and in fact reduces to pure bond percolation for asymptotically large external fields. The same percolation phase transition in QCD with physical quarks, and even towards the chiral limit, could thus yield a clear distinction between confined and deconfined phases. The gauge invariance of the spanning probability as the order parameter for this geometric phase transition ensures that physical states remain colorless at all temperatures and densities. We explicitly illustrate the mechanism in the flux-tube model representation of the effective theory for QCD at strong coupling with heavy quarks where the spannig probability can be calculated numerically at reasonable cost.