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...cal mechanism [4]. It is then interesting to investigate whether magnetic monopoles affect fermionic theories, and, in particular, the physics of chiral symmetry breaking and restoration. The work of =-=[5]-=- provides a theoretical framework for the study of the interplay of monopole and fermion dynamics, and a numerical strategy for its quantitative verification. Unfortunately, it has not been developed ...

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...s trivial, the most natural candidate to describe the data is an equation of state à la Nambu-Jona-Lasinio. We will use the following form, which is motivated by the leading term of the 1/N expansion =-=[42]-=-: am0 = a NJL (κ − κc)〈χχ〉 + b NJL 〈χχ〉 3 (log〈χχ〉/s) (23) and we will just comment on its possible generalizations [46,47] (in practical analysis log〈χχ〉/s will be replaced by log〈χχ〉 + c). In many c...

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...l density is pc = 0.161. In our model the density pm,c at the percolation phase transition depends on β, and it is generally lower. Our result is close to that of site bond percolation γ/ν = 2.094(2) =-=[41,40]-=-. Considering the vector character of the monopole current, we should not expect that the two models are in the same universality class, as pointed out in [6]). To determine βperc/νperc we investigate...

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...ities, equation of state and the meson masses. The data have been obtained in Monte Carlo runs for a simultaneous investigation of the gauge-ball spectrum in the pure U(1) gauge theory in both phases =-=[17]-=-. For that purpose we have accumulated a large number of gauge field configurations at 17 β-points on lattices up to 20 3 40 (further details are given in [17]). All these points are close to the phas...

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... measurements we have also determined various fermionic observables in the quenched approximation. This is aimed at a study of the U(1) theory with staggered fermions and will be published separately =-=[29]-=-. 83 Static potential 3.1 Measurement of the static potential In the static potential analysis we include Wilson loop expectation values whose noise to signal ratio is smaller than 20% of the expecta...

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...tion, very similar to the phase diagram of the U(1) theory, has been pointed out in [41]. 31are other examples in lattice models where such endpoints are associated with Gaussian behaviour (see e.g. =-=[42]-=-). Depending on the choice from the above scenarios where the 0 ++ gauge-ball in the U(1) theory scales, either the TCP or the critical line at γ < γ 0 might be analogous to such endpoints. 7 The spec...

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...ormalization group transformation matrix, consistent with the values (1) and (2) of the critical exponents, was observed back in the eighties in Monte Carlo renormalization group studies of the model =-=[11,12]-=-. These exponents can now be interpreted in terms of the scaling of physical observables. In the Coulomb phase we find evidence that in the vicinity of the phase transition, apart from the massless ve...

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... non-Gaussian one. Recently, evidence has been provided, that in the coupling space enlarged by monopole coupling, a second order phase transition with non-Gaussian critical exponents may be observed =-=[21]-=-. Because of the doubts as to whether a continuum limit can be obtained, calculations of the spectrum of the model are sporadic. The massless photon in the Coulomb phase was observed in various studie...

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...al to suppose the special behaviour is due to the endpoint itself. There 2 The possibility of a different interpretation, very similar to the phase diagram of the U(1) theory, has been pointed out in =-=[41]-=-. 31are other examples in lattice models where such endpoints are associated with Gaussian behaviour (see e.g. [42]). Depending on the choice from the above scenarios where the 0 ++ gauge-ball in the...

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...esults are shown in Table 2, first line. We get κc = .874(6), δ = 2.12(15), and βχ = 0.88(5). (These exponents are very close to those of quenched, non-compact QED: δ = 2.12(1), βχ = 0.86(3), γ = 1.0 =-=[45,35]-=-.) Assuming scaling, these critical exponents give ν = .695. We have verified that the fit is stable against the inclusion of the two points at am0 = .02, κ = .80 and .95. Finally, since we want to co...