Interplay of monopoles and chiral symmetry breaking in noncompact lattice QED

Noncompact lattice QED is simulated for varoius numbers of fermion species Nf ranging from 8 through 40 by the exact hybrid Monte Carlo algorithm. Over this range of Nf, chiral symmetry breaking is found to be strongly correlated with the effective monopoles in the theory. For Nf between 8 and 16 the chiral symmetry breaking and monopole percolation transitions are second order and coincident. Assuming power law critical behavior, the correlation length exponent for the chiral transition is identical to that of monopole percolation. This result supports the conjecture that monopole percolation open-quote open-quote drives close-quote close-quote the nontrivial chiral transition. For Nf between 20 and 32, the monopoles experience a first-order condensation transition coincident with a first-order chiral transition. For Nf as large as 40 both transitions are strongly suppressed. The data at large Nf(Nf approx-gt 20) are interpreted in terms of a strongly interacting monopole gas-liquid transition. copyright 1996 The American Physical Society