J. Jersák

U(1) lattice gauge theory near the phase transition

Abstract The U(1) lattice gauge theory with the Wilson action is investigated in a high statistics Monte Carlo calculation in the close proximity of the deconfinement phase transition. On a 16 4 lattice, we obtain the renormalized charge e r in the Coulomb phase with a maximal value e 2 r /4 π = 0.195 ± 0.01 at the phase transition point β T = 1.0106 ± 0.0018. The mean plaquette develops a small hysteresis. On a 6 4 lattice, two metastable states can clearly be seen. This suggests that the phase transition could be of first order.

Decoupling Doublers of Chiral Lattice Fermions in a Quenched Fermion Higgs Model

Abstract We study in the quenched approximation the fermion-scalar sector of a lattice version of the standard model in the broken symmetry phase using a Wilson-Yukawa coupling to deal with the fermion doubling. For relatively strong but fixed Wilson-Yukawa coupling the fermion doublers can be easily decoupled as the critical point is approached by giving them masses of the order of the cutoff.

THE CRITICAL EXPONENTS OF THE DECONFINEMENT TRANSITION IN SU(2) LATTICE GAUGE THEORY

Abstract The behaviour of the deconfinement order parameter, the susceptibility, the correlation length and the energy density of the SU(2) Yang-Mills system is studied in the neighbourhood of the deconfinement transition on large lattices (18 3 × 3,4,5 and 16 3 × 4,5,6). We check the critical exponents both below and above the transition by fits including corrections-to-scaling terms and find very good agreement with the universality predictions from the Z 2 spin system. With the predicted exponent β as input, precise values for the critical temperature are found; they are confirmed by the energy density results.

Charge renormalization in compact lattice QED

Abstract The potential between static test charges in compact lattice U(1) gauge theory is determined in a Monte Carlo calculation for both the Wilson and the Villain form of the action on 16 4 and 14 4 lattices, respectively. At the phase transition point we find a finite value of the renormalized charge in the Coulomb phase, α T =0.20 (with a systematic error of 0.02), which agrees for both actions. The string tension is investigated in the confinement phase, and the values agree for both actions within exponent describing its decrease, are determined. Also these values agree for both actions within error bars, and their average is ν t = 0.31±0.03.

Goldstone bosons and finite size effects: A numerical study of the O(4) model

We study the 4-component φ4 model in 4 dimensions in the broken phase where the Goldstone modes dominate the finite size effects. Chiral perturbation theory relates the quantities measured at non-vanishing external source and in a finite volume to the low energy parameters v (the field expectation value) and F (the pion decay constant) defined at infinite volume in the limit of vanishing external source. We analyze high statistics Monte Carlo data for the field expectation value and the Goldstone propagator by means of such expansions and we find very good agreement with the theoretically expected functional behaviour. It is possible to identify non-leading terms in the finite volume expansion and determine corresponding scale parameters. We also explore some alternative methods applicable at vanishing external source. Our analysis demonstrates that in a situation where the light Goldstone bosons control the dynamics of the system at large distances one may determine the infinite volume, zeri external source quantities from finite volume simulations in a theoretically controlled way.

Scaling analysis of the magnetic monopole mass and condensate in the pure U(1) lattice gauge theory

We observe the power law scaling behavior of the monopole mass and condensate in the pure compact U(1) gauge theory with the Villain action. In the Coulomb phase the monopole mass scales with the exponent

Finite temperature SU(2) Higgs model on a lattice

{\ensuremath{\nu}}_{\mathrm{m}}=0.49(4)

Non-Gaussian Fixed Point in Four-Dimensional Pure Compact U(1) Gauge Theory on the Lattice.

. In the confinement phase the behavior of the monopole condensate is described with remarkable accuracy by the exponent

Finite Size Effects and Spontaneously Broken Symmetries: The Case of the 0(4) Model

{\ensuremath{\beta}}_{\mathrm{exp}}=0.197(3)

PHOTON AND BOSONIUM MASSES IN SCALAR LATTICE QED

. Possible implications of these phenomena for a construction of a strongly coupled continuum U(1) gauge theory are discussed.