Tsuneo Suzuki

Monopoles and string tension in SU(2) QCD

Abstract Monopole and photon contributions to abelian Wilson loops are calculated using Monte Carlo simulations of SU (2) QCD in the maximally abelian gauge. The string tension is well reproduced only by monopole contributions, whereas photons alone are responsible for the Coulomb coefficient of the abelian static potential.

Monopoles and confinement

Abstract I give a minireview of numerical studies of abelian monopoles and QCD confinement, suggesting that QCD confinement is interpreted as the dual Meissner effect due to condensation of abelian monopoles.

Monopole action and condensation in SU(2) QCD

Abstract An effective monopole action for various extended monopoles is derived from vacuum configurations after abelian projection in the maximally abelian gauge in SU(2) QCD. The action is independent of the lattice volume chosen. Moreover, it depends only on the physical lattice spacing of the renormalized lattice, not on β. Entropy dominance over the energy of monopole loops is seen on the renormalized lattice with the spacing b > b c ⋍ 5.2 × 10 −3 Λ L −1 . This suggests that monopole condensation always (for all β) occurs in the infinite-volume limit of lattice QCD

Monopole action from vacuum configurations in compact QED

Abstract It is possible to derive a monopole action from vacuum configurations obtained in Monte Carlo simulations extending the method developed by Swendsen. We apply the method to compact QED both in the Villain and in the Wilson forms. The action of the natural monopoles in the Villain case is in fairly good agreement with that derived by the exact dual transformation. Comparing the monopole actions, we find (1) the DeGrand-Toussaint monopole definition may be useful for β v larger than about 0.5, (2) the Villain model well approximates the Wilson one for β smaller than β c and (3) in the Wilson action the monopole condensation occurs in the confinement phase and β c may be explained by the energy-entropy balance of monopole loops like in the Villain case.

The (dual) Meissner effect in SU(2) and SU(3) QCD

After making an abelian projection in the maximally abelian gauge, we measure the distribution of abelian electric flux and monopole currents around an abelian Wilson loop in SU(2) and SU(3) QCD. The (dual) Meissner effect is observed clearly. The vacua in the confinement phases of SU(2) and SU(3) are both at around the border between type-1 and type-2 (dual) superconductor.

Gauge-fixing ambiguity and monopole number

Abstract Gauge-fixing ambiguities of lattice SU (2) QCD are studied in the maximally abelian and unitary gauges. In the former, we find local maxima of a gauge-fixing function which may correspond to Gribov copies. There is a definite anti-correlation between the number of monopoles and the value of the function. Errors of measured quantities coming from the ambiguity are found to be less than inherent dispersion in the ensemble average. No ambiguity is found in the unitary gauges.

Polyakov loops and monopoles in QCD

Abstract Monte Carlo simulations of abelian projection of T ≠ 0 pure lattice QCD show that 1) Polyakov loops written in terms of abelian link fields alone play the role of an order parameter of deconfinement transition, 2) the abelian Polyakov loops are decomposed into contributions from Dirac strings of monopoles and from photons, 3) vanishing of the abelian Polyakov loops in the confinement phase is due to the Dirac strings alone and the photons give a finite contribution in both phases. Moreover, these results appear to hold good with any abelian projection as seen from the studies in the maximally abelian gauge and in various unitary gauges.

Monopole action and monopole condensation in SU(3) lattice QCD

Abstract Effective monopole actions for various extended monopoles are derived from vacuum configurations after abelian projection in the maximally abelian gauge in T = 0 and T ≠ 0 SU(3) lattice QCD. The actions obtained appear to be independent of the lattice volume adopted. At zero temperature, monopole condensation is seen to occur from energy-entropy balance in the strong coupling region. Larger β is included in the monopole condensed phase as more extended monopoles are considered. The scaling seen in the SU(2) case is not yet observed. The renormalization flow diagram suggests the existence of an infrared fixed point. A hysteresis behavior is seen around the critical temperature in the case of the T ≠ 0 action.

A static baryon in a dual abelian effective theory of QCD

Abstract The potential of a static baryon is studied numerically in a dual abelian effective theory of QCD. The Dirac quantization condition forbids Δ-type flux. Minimizing the vacuum energy with respect to various flux distributions, we find that a baryon carries Y- or Λ-type flux according to the configuration of the quarks. The flux is squeezed as expected when monopole condensation occurs. The potential evaluated is slightly different from that usually assumed as the summation of the two-body potentials.

Monopole condensation and confinement in SU (2) QCD

An effective monopole action is derived from vacuum configurations after abelian projection in the maximally abelian gauge in SU (2) QCD. Entropy dominance over energy of monopole loops is seen on the renormalized lattice with the spacing b >bc ≅ 5.2 × 10−3λL−1 when the physical volume of the system is large enough. Monopole and photon contributions to Wilson loops are calculated also. The string tensions of SU (2) QCD are well reproduced by extended monopole contributions alone.