arXiv subjects

U. J. Wiese

Publications and source records attributed to U. J. Wiese.

5 recordsLinked to original sources

arXiv2022

A New Type of Lattice Gauge Theory through Self-adjoint Extensions

A generalization of Wilsonian lattice gauge theory may be obtained by considering the possible self-adjoint extensions of the electric field operator in the Hamiltonian formalism. In the special case of 3D $\mathrm{U}(1)$ gauge theory these are parametrised by a phase $θ$, and the ordinary Wilson theory is recovered for $θ=0$. We consider the case $θ=π$, which, upon dualization, turns into a theory of staggered integer and half-integer height variables. We investigate order parameters for the breaking of the relevant symmetries, and thus study the phase diagram of the theory, which shows evidence of a broken $\mathbb{Z}_2$ symmetry in the continuum limit, in contrast to the ordinary theory.

hep-lat↗

arXiv2022

Confined Charged Particles in C-periodic Volumes

Charged particles in an Abelian Coulomb phase are non-local infraparticles that are surrounded by a cloud of soft photons which extends to infinity. Gauss' law prevents the existence of charged particles in a periodic volume. In a $C$-periodic volume, which is periodic up to charge conjugation, on the other hand, charged particles can exist. This includes vortices in the $3$-d XY-model, magnetic monopoles in $4$-d $\mathrm{U}(1)$ gauge theory, as well as protons and other charged particles in QCD coupled to QED. In four dimensions non-Abelian charges are confined. Hence, in an infinite volume non-Abelian infraparticles cost an infinite amount of energy. However, in a $C$-periodic volume non-Abelian infraparticles (whose energy increases linearly with the box size) can indeed exist. Investigating these states holds the promise of deepening our understanding of confinement.

hep-lat↗

arXiv2004

Study of the 2-d CP(N-1) models at θ=0 and π

We present numerical results for 2-d CP(N-1) models at θ=0 and πobtained in the D-theory formulation. In this formulation we construct an efficient cluster algorithm and we show numerical evidence for a first order transition for CP(N-1\geq 2) models at θ= π. By a finite size scaling analysis, we also discuss the equivalence in the continuum limit of the D-theory formulation of the 2-d CP(N-1) models and the usual lattice definition.

hep-lat↗

arXiv2004

Study of CP(N-1) θ-Vacua by Cluster-Simulation of SU(N) Quantum Spin Ladders

D-theory provides an alternative lattice regularization of the (1+1)-d CP(N-1) quantum field theory. In this formulation the continuous classical CP(N-1) fields emerge from the dimensional reduction of discrete SU(N) quantum spins. In analogy to Haldane's conjecture, ladders consisting of an even number of transversely coupled spin chains lead to a CP(N-1) model with vacuum angle θ= 0, while an odd number of chains yields θ= π. In contrast to Wilson's formulation of lattice field theory, in D-theory no sign problem arises at θ= π, and an efficient cluster algorithm is used to investigate the θ-vacuum effects. At θ= πthere is a first order phase transition with spontaneous breaking of charge conjugation symmetry for CP(N-1) models with N>2.

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↗