Showing papers by "Manfried Faber published in 1998"
TL;DR: In this article, the authors show that center vortices identified in the Yang-Mills vacuum state account for the full asymptotic string tension in SU(3) lattice gauge theory.
Abstract: We discuss the implementation of the ``direct'' maximal center gauge (a gauge which maximizes the lattice average of the squared-modulus of the trace of link variables), and its use in identifying ${Z}_{2}$ center vortices in Yang-Mills vacuum configurations generated by lattice Monte Carlo calculations. We find that center vortices identified in the vacuum state account for the full asymptotic string tension. Scaling of vortex densities with lattice coupling, change in vortex size with cooling, and sensitivity to Gribov copies are discussed. Preliminary evidence is presented, on small lattices, for center dominance in SU(3) lattice gauge theory.
188 citations
TL;DR: In this paper, it was shown that the deviations from exact Casimir scaling, which tend to grow with loop size, become much more pronounced as the dimensionality of the group representation increases.
Abstract: We argue that the approximate {open_quotes}Casimir scaling{close_quotes} of the string tensions of higher-representation Wilson loops is an effect due to the finite thickness of center vortex configurations. It is shown, in the context of a simple model of the Z{sub 2} vortex core, how vortex condensation in Yang-Mills theory can account for both Casimir scaling in intermediate size loops and color-screening in larger loops. An implication of our model is that the deviations from exact Casimir scaling, which tend to grow with loop size, become much more pronounced as the dimensionality of the group representation increases. {copyright} {ital 1998} {ital The American Physical Society}
131 citations
TL;DR: In this article, the dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for the calculation of expectation values in the presence of external charges.
Abstract: The dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for the calculation of expectation values in the presence of external charges. Applying the dual simulation to flux tubes for charge distances up to around 20 lattice spacings, we find a deviation from the behavior of a dual type-II superconductor in the London limit at large distances. The roughening of the flux tube agrees with the effective string picture of confinement. Further we show that finite temperature effects are negligible for time extents larger than the charge distance. Finally we analyze the different contributions to the total energy of the electromagnetic field. The parallel component of the magnetic field turns out to have the strongest influence on the deviation from the linear behavior at small charge distances. {copyright} {ital 1997} {ital The American Physical Society}
36 citations
TL;DR: In this paper, the authors consider projections of SU(2) lattice link variables onto center and U(1) subgroups, with and without gauge-fixing, and show that the static quark potential extracted from projected variables agrees exactly with the full link variables.
Abstract: We consider projections of SU(2) lattice link variables onto Z(2) center and U(1) subgroups, with and without gauge-fixing. It is shown that in the absence of gauge-fixing, and up to an additive constant, the static quark potential extracted from projected variables agrees exactly with the static quark potential taken from the full link variables; this is an extension of recent arguments by Ambjorn and Greensite, and by Ogilvie. Abelian and center dominance is essentially trivial in this case, and seems of no physical relevance. The situation changes drastically upon gauge fixing. In the case of center projection, there are a series of tests one can carry out, to check if vortices identified in the projected configurations are physical objects. All these criteria are satisfied in maximal center gauge, and we show here that they all fail in the absence of gauge fixing. The non-triviality of center projection is due entirely to the maximal center gauge-fixing, which pumps information about the location of extended physical objects into local Z(2) observables.
17 citations
TL;DR: In this paper, singly and doubly charged flux tubes in U (1) lattice gauge theory were investigated and it was shown that the string tension in both three and four dimensions scales proportionally to the charge.
11 citations
01 Apr 1998
TL;DR: In this article, a method for locating center vortices (fluxons) in thermalized lattice gauge field configurations was presented, and it was shown that the asymptotic string tension of fundamental-representation Wilson loops is due to fluctuations in the number of center Vortices linking those loops.
Abstract: We present a method for locating center vortices (“fluxons”) in thermalized lattice gauge field configurations. We find evidence, in lattice Monte Carlo simulations, that the asymptotic string tension of fundamental-representation Wilson loops is due to fluctuations in the number of center vortices linking those loops.
9 citations
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TL;DR: In this paper, it was shown that the string tension of an adjoint Wilson loop vanishes, if the loop is evaluated in a sub-ensemble of configurations in which no center vortex links the loop.
Abstract: Wilson loops in the adjoint representation are evaluated on cooled lattices in SU(2) lattice gauge theory. It is found that the string tension of an adjoint Wilson loop vanishes, if the loop is evaluated in a sub-ensemble of configurations in which no center vortex links the loop. This result supports our recent proposal that the adjoint string tension, in the Casimir-scaling regime, can be attributed to a center vortex mechanism.
5 citations
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TL;DR: In this article, the relativistic field theory model of the deuteron (RFMD) is applied to the calculation of the astrophysical factor S(pp)(0) for the process of the solar proton burning p + p -> D + e^+ +
u_e and the cross sections for the disintegration by photons gamma + D -> n + p and anti-neutrinos \bar{
u}_e + D-> e+ + n + n.
Abstract: The relativistic field theory model of the deuteron (RFMD) is applied to the calculation of the astrophysical factor S_{pp}(0) for the process of the solar proton burning p + p -> D + e^+ +
u_e and the cross sections for the disintegration of the deuteron by photons gamma + D -> n + p and anti-neutrinos \bar{
u}_e + D -> e^+ + n + n. Our theoretical value of the astrophysical factor S_{pp}(0) = 4.02 x 10^{-25} MeV b agrees with the classical result obtained by Bahcall and Kamionkowski S_{pp}(0) = 3.89 x 10^{-25} MeV b in the potential model approach (PMA). The cross sections for the disintegration of the deuteron by photons and anti-neutrinos calculated near thresholds are in good agreement with the PMA. An extrapolation of the cross sections for energies far from thresholds is suggested and related to the inclusion of form factors describing spatial smearing of the deuteron and the NN system. The extrapolated cross section for the disintegration of the deuteron by anti-neutrinos agrees with that calculated in the PMA in the anti-neutrino energy region from threshold up to 10 MeV. The extrapolated cross section averaged over the reactor anti-neutrino energy spectrum is obtained in agreement with the experimental data. It is shown that the RFMD enables to describe elastic low-energy NN scattering in accordance with low-energy nuclear phenomenology.
5 citations
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TL;DR: In this paper, a generalized version of the relativistic field theory model of the deuteron (RFMD) is applied to the description of processes of astrophysical interest and low-energy elastic NN scattering.
Abstract: The generalized version of the relativistic field theory model of the deuteron (RFMD) is applied to the description of processes of astrophysical interest and low-energy elastic NN scattering. The value of the astrophysical factor S_{pp}(0) = 5.52x10^{-25} MeV b is found to be enhanced by a factor of 1.42 with respect to the classical value S^*_{pp}(0) = 3.89x10{-25} MeV b obtained by Kamionkowski and Bahcall in the potential model approach (PMA). The astrophysical aspects of this enhancement are discussed. The cross sections for the disintegration of the deuteron by (anti-) neutrinos nu_e + D -> e^- + p + p, anti-nu_e + D -> e^+ + n + n and nu_e(anti-nu_e) + D -> nu_e(anti-nu_e) + n + p are calculated for the energies of (anti-) neutrinos ranging from thresholds up to 10 MeV. The results are discussed in comparison with the PMA data. The cross sections for anti-nu_e + D -> e^+ + n + n and anti-nu_e + D -> anti-nu_e + n + p averaged over the reactor anti-neutrino energy spectrum agree well with experimental data. The astrophysical factor S_{pep}(0) for the process p + e^- + p -> nu_e + D (or pep-process) is calculated relative to S_{pp}(0) in complete agreement with the result obtained by Bahcall and May. The reaction rate for the neutron-proton radiative capture is calculated in agreement with the PMA result obtained for pure M1 transition. It is shown that in the RFMD one can describe low--energy elastic NN scattering in complete agreement with low-energy nuclear phenomenology.
5 citations
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TL;DR: In this paper, the authors present numerical evidence that supports the theory of quark confinement based on center vortex condensation, and introduce a special gauge (maximal center gauge) and center projection, suitable for identification of center vortices.
Abstract: We present numerical evidence that supports the theory of quark confinement based on center vortex condensation. We introduce a special gauge ("maximal center gauge") and center projection, suitable for identification of center vortices. Main focus is then put on the connection of vortices in center projection to "confiners" in full, unprojected gauge-field configurations. Topics briefly discussed include: the relation between vortices and monopoles, first results for SU(3), and the problem of Casimir scaling.
2 citations
TL;DR: In this article, the magnetic monopole condensate was calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.
Abstract: The magnetic monopole condensate is calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.[1,2] as a functional of the dual Dirac string shape. The calculation is carried out in the tree approximation in the scalar monopole-antimonopole collective excitation field. The integration over quantum fluctuations of the dual-vector monopole-antimonopole collective excitation field around the Abrikosov flux line and string shape fluctuations are performed explicitly. We claim that there are important contributions of quantum and string shape fluctuations to the magnetic monopole condensate.
TL;DR: In this article, the standard Wilson action of SU (3) lattice gauge theory was modified by adding an extra term which suppresses colour magnetic currents, and numerical results of simulations at zero and finite temperature were presented.
01 Apr 1998
TL;DR: In this article, the authors consider pure gluonic SU (3) lattice gauge theory and determine colour magnetic currents by measuring the total magnetic flux out of unit lattice cubes.
Abstract: We consider pure gluonic SU (3) lattice gauge theory and determine colour magnetic currents by measuring the total magnetic flux out of unit lattice cubes. To study the influence of these currents on physical quantities we modify the Wilson action and add an extra term suppressing the currents. We present first results of numerical simulations which show that a suppression of magnetic currents strongly influences the string tension and the critical coupling for the finite temperature phase transition.
01 Apr 1998
TL;DR: In this article, the dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for a numerical investigation of multiply charged systems and the interaction between flux tubes.
Abstract: The dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for a numerical investigation of multiply charged systems and the interaction between flux tubes For this aim, it is convenient to implement periodically closed flux tubes (torelons) in the dual formulation We calculate the free energy as well as the total electro-magnetic energy of doubly charged flux tubes as a function of the coupling β The main results are that the string tension scales proportionally to the charge (contrary to the Coulomb potential) and in the range 09
01 Apr 1998
TL;DR: In this article, the phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality, and properties of chromoelectric and chromomagnetic sectors of the theory are discussed.
Abstract: The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. We discuss properties of chromoelectric and chromomagnetic sectors of the theory and show whereas electric charges carrying a unit of Z(Nc) charge are screened at high temperatures via dynamical matter loops, this is not the case for the Z(Nc) magnetic flux. An order parameter is constructed to probe the realization of localZ(Nc) symmetry in the magnetic sector. We argue this order parameter may be used to detect the deconfinement phase transition which is defined in terms of the screening mechanism.
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TL;DR: In this paper, the phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality, and a proper quantity which is able to reveal a critical behaviour of the theory with fundamental quarks is introduced.
Abstract: The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. Since this ensemble implies a projection to the zero triality sector of the theory we introduce a proper quantity which is able to reveal a critical behaviour of the theory with fundamental quarks. We discuss the properties of both the chromoelectric and chromomagnetic sectors of the theory and show while electric charges carrying a unit of Z(N) charge are screened at high temperatures by dynamical matter loops, this is not the case for the Z(N) magnetic flux. An order parameter is constructed to probe the realization of local discrete Z(N) symmetry in the magnetic sector. We argue it can be used to detect a deconfinement phase being defined in terms of the screening mechanism as a phase of unscreened Z(N) flux. It may be detectable at long range via the Aharonov-Bohm effect. We discuss the possible phase structure of QCD in this approach.