arXiv subjects

M. L. Laursen

Publications and source records attributed to M. L. Laursen.

10 recordsLinked to original sources

arXiv1993

Thermal Fluctuations of Chern-Simons Numbers in the Lattice SU(2) Higgs Model

We study the temperature dependence of the Chern-Simons number fluctuations in the SU(2) Higgs Model on Euclidean lattices with spatial sizes up to 20^3. Temperatures well above the Higgs phase transition $T_H$ are achieved on anisotropic lattices. Numerical results are compared to perturbative results on finite lattices as well as in continuum perturbation theory. We find qualitative agreement with perturbative estimates and see at high temperatures a tendency towards static configurations. Up to temperatures $T \simeq 2T_H$ we find indication that tunneling between vacuums with different Chern-Simons numbers are still exponentially suppressed. (Full PostScript file available via Email from plache@physw.uni-bielefeld.de )

hep-lat↗

arXiv1993

Vacuum Tunneling and Periodic Structure in Lattice Higgs Models

Using a geometric definition for the lattice Chern-Simons term in even dimensions, we have studied the distribution of Chern-Simons numbers for the 2d-U(1) and the 4d-SU(2) lattice Higgs models. The periodic structure of the distributions is preserved in our lattice formulation and has been examined in detail. In both cases the finite size effects visible in the distribution of Chern-Simons numbers are well accounted for by the Haar measure. Moreover, we find that $\langle N_{CS}^2 \rangle$ grows with the spatial volume. We also find numerical evidence that tunneling in 4d is increased at high temperature. (PS-File including Figures available via E-mail: plache@physv.uni-bielefeld.de)

hep-lat↗

arXiv1993

The Confined-Deconfined Interface Tension in Quenched QCD using the Histogram Method

We present results for the confinement-deconfinement interface tension $σ_{cd}$ of quenched QCD. They were obtained by applying Binder's histogram method to lattices of size $L^2\times L_z\times L_t$ for $L_t=2$ and $L=8,10,12\mbox{ and }14$ and various $L_z\in [L,\, 4\, L]$. The use of a multicanonical algorithm and rectangular geometries have turned out to be crucial for the numerical studies. We also give an estimate for $σ_{cd}$ at $L_t=4$ using published data.

hep-lat↗

arXiv1992

The confined-deconfined interface tension, wetting, and the spectrum of the transfer matrix

The reduced tension $σ_{cd}$ of the interface between the confined and the deconfined phase of $SU(3)$ pure gauge theory is determined from numerical simulations of the first transfer matrix eigenvalues. At $T_c = 1/L_t$ we find $σ_{cd} = 0.139(4) T_c^2$ for $L_t = 2$. The interfaces show universal behavior because the deconfined-deconfined interfaces are completely wet by the confined phase. The critical exponents of complete wetting follow from the analytic interface solutions of a $\Z(3)$-symmetric $Φ^4$ model in three dimensions. We find numerical evidence that the confined-deconfined interface is rough.

hep-lat↗

arXiv1992

The Interface Tension in Quenched QCD at the Critical Temperature

We present results for the confinement-deconfinement interface tension $α_{cd}$ of quenched QCD. They were obtained by applying Binder's histogram method to lattices of size $L^2\times L_z\times L_t$ for $L_t=2$ and $L=8,10,12\mbox{ and }14$ with $L_z=30$ for $L=8$ and $L_z=3L$ otherwise. The use of a multicanonical algorithm and cylindrical geometries have turned out to be crucial for the numerical studies.

hep-lat↗

arXiv1992

Chern-Simons term in the 4-dimensional SU(2) Higgs Model

Using Seiberg's definition for the geometric charge in SU(2) lattice gauge theory, we have managed to apply it also to the Chern-Simons term. We checked the periodic structure and determined the Chern-Simons density on small lattices $L^4$ and $L^3 \times 2,\, 4$ with $L=4,\, 6,\mbox{ and }8$ near the critical region in the SU(2) Higgs model. The data indicate that tunneling is increased at high temperature.

hep-lat↗

arXiv1992

Chern-Simons term and Topological Charge on the Lattice

In a somewhat overlooked work by Seiberg, a definition of the topological charge for SU(N) lattice fields was given. Here, it is shown that Seibergs and Lüschers charge definition are related up to the section of the bundle. With the continued interest in baryon number violating processes, Seibergs paper is useful since it allows for a Chern-Simons number also.

hep-lat↗

arXiv1992

The confined-deconfined Interface Tension and the Spectrum of the Transfer Matrix

The reduced tension $σ_{cd}$ of the interface between the confined and the deconfined phase of $SU(3)$ pure gauge theory is related to the finite size effects of the first transfer matrix eigenvalues. A lattice simulation of the transfer matrix spectrum at the critical temperature $T_c = 1/L_t$ yields $σ_{cd} = 0.139(4) T_c^2$ for $L_t = 2$. We found numerical evidence that the deconfined-deconfined domain walls are completely wet by the confined phase, and that the confined-deconfined interfaces are rough.

hep-lat↗

arXiv1992

Chern-Simons term in the 4-dimensional SU(2) Higgs model

Using a variation of Lueschers geometric charge definition for SU(2) lattice gauge theory, we have managed to give a geometric expression for it's Chern-Simons ter. From this definition we have checked the periodic structure. we determined the Chern-Simons density for symmetric and asymmetric lattices near the critical region in the SU(2) Higgs model. The data indicate that tunneling is increased at high temperature.

hep-lat↗

arXiv1992

A Multicanonical Algorithm and the Surface Free Energy in SU(3) Pure Gauge Theory

We present a multicanonical algorithm for the SU(3) pure gauge theory at the deconfinement phase transition. We measure the tunneling times for lattices of size L^3x2 for L=8,10, and 12. In contrast to the canonical algorithm the tunneling time increases only moderately with L. Finally, we determine the interfacial free energy applying the multicanonical algorithm.

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