Christof Gattringer
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View article: U(1)-gauged 2-flavor spin system in 3-D
U(1)-gauged 2-flavor spin system in 3-D Open
We study a U(1)-gauged 2-component spin system in 3 dimensions. For the gauge fields we use the Villain formulation with a constraint that removes lattice monopoles and in this form couple the gauge fields to 2-component spins. We discuss …
View article: U(1)-gauged 2-flavor spin system in 3-D
U(1)-gauged 2-flavor spin system in 3-D Open
We study a U(1)-gauged 2-component spin system in 3 dimensions. For the gauge fields we use the Villain formulation with a constraint that removes lattice monopoles and in this form couple the gauge fields to 2-component spins. We discuss …
View article: Massless Schwinger model with a 4-fermi interaction at topological angle $\theta = \pi$
Massless Schwinger model with a 4-fermi interaction at topological angle $\theta = \pi$ Open
We study the massless Schwinger model with an additional 4-fermi interaction and a topological term. For topological angle $\\theta = \\pi$ charge conjugation symmetry is implemented in a non-trivial way and we study the possibility of its…
View article: Density of states techniques for fermion worldlines
Density of states techniques for fermion worldlines Open
Worldline representations were established as a powerful tool for studying bosonic lattice field theories at finite density. For fermions, however, the worldlines still may carry signs that originate from the Dirac algebra and from the Gra…
View article: Density of states techniques for fermion worldlines
Density of states techniques for fermion worldlines Open
Worldline representations were established as a powerful tool for studying bosonic lattice field theories at finite density. For fermions, however, the worldlines still may carry signs that originate from the Dirac algebra and from the Gra…
View article: Massless Schwinger model with a 4-fermi interaction at topological angle $θ= π$
Massless Schwinger model with a 4-fermi interaction at topological angle $θ= π$ Open
We study the massless Schwinger model with an additional 4-fermi interaction and a topological term. For topological angle $θ= π$ charge conjugation symmetry is implemented in a non-trivial way and we study the possibility of its spontaneo…
View article: Phase structure of self-dual lattice gauge theories in 4d
Phase structure of self-dual lattice gauge theories in 4d Open
View article: Density of states approach for lattice field theory with topological terms
Density of states approach for lattice field theory with topological terms Open
We discuss a new density of states (DoS) approach to solve the complex action problem that is caused by topological terms. The key ingredient is to use open boundary conditions for (at least) one of the directions, such that the quantizati…
View article: Self-dual U(1) lattice field theory with a θ-term
Self-dual U(1) lattice field theory with a θ-term Open
View article: Self-dual U(1) lattice field theory with a $\\theta$-term
Self-dual U(1) lattice field theory with a $\\theta$-term Open
We study U(1) gauge theories with a modified Villain action. Such theories\ncan naturally be coupled to electric and magnetic matter, and display exact\nelectric-magnetic duality. In their simplest formulation without a\n$\\theta$-term, su…
View article: Density of states approach for lattice field theory with topological\n terms
Density of states approach for lattice field theory with topological\n terms Open
We discuss a new density of states (DoS) approach to solve the complex action\nproblem that is caused by topological terms. The key ingredient is to use open\nboundary conditions for (at least) one of the directions, such that the\nquantiz…
View article: Density of states approach for lattice field theory with topological terms
Density of states approach for lattice field theory with topological terms Open
We discuss a new density of states (DoS) approach to solve the complex action problem that is caused by topological terms. The key ingredient is to use open boundary conditions for (at least) one of the directions, such that the quantizati…
View article: Numerical simulation of self-dual U(1) lattice field theory with electric and magnetic matter
Numerical simulation of self-dual U(1) lattice field theory with electric and magnetic matter Open
We study a recently proposed formulation of U(1) lattice field theory with electric and magnetic matter based on the Villain formulation. This discretization allows for a duality that gives rise to relations between weak and strong gauge c…
View article: First-Principles Simulations of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mi mathvariant="normal">D</mml:mi></mml:mrow></mml:math> Quantum Field Theories at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>θ</mml:mi><mml:mo>=</mml:mo><mml:mi>π</mml:mi></mml:math> and Spin Chains
First-Principles Simulations of Quantum Field Theories at and Spin Chains Open
We present a lattice study of a 2-flavor U(1) gauge-Higgs model quantum field theory with a topological term at θ=π. Such studies are prohibitively costly in the standard lattice formulation due to the sign problem. Using a novel discretiz…
View article: Density of states approach for lattice gauge theory with a θ-term
Density of states approach for lattice gauge theory with a θ-term Open
We discuss a new strategy for treating the complex action problem of lattice field theories with a θ-term based on density of states (DoS) methods. The key ingredient is to use open boundary conditions where the topological charge is not q…
View article: Exploring the worldline formulation of the Potts model
Exploring the worldline formulation of the Potts model Open
We revisit the issue of worldline formulations for the q-state Potts model and discuss a worldline representation in arbitrary dimensions which also allows for magnetic terms. For vanishing magnetic field we implement a Hodge decomposition…
View article: Density of states approach for lattice QCD with a $\theta$-term
Density of states approach for lattice QCD with a $\theta$-term Open
We discuss a new strategy for treating the complex action problem of lattice field theories with a $\theta$-term based on density of states (DoS) methods. The key ingredient is to use open boundary conditions where the topological charge i…
View article: New Canonical and Grand Canonical Density of States Techniques for Finite Density Lattice QCD
New Canonical and Grand Canonical Density of States Techniques for Finite Density Lattice QCD Open
We discuss two new density of states approaches for finite density lattice QCD (Quantum Chromo Dynamics). The paper extends a recent presentation of the new techniques based on Wilson fermions, while here, we now discuss and test the case …
View article: Symmetries of the light hadron spectrum in high temperature QCD
Symmetries of the light hadron spectrum in high temperature QCD Open
Properties of QCD matter change significantly around the chiral crossover temperature, and the effects on $U(1)_A$ and topological susceptibilities, as well as the meson spectrum have been studied with much care. Baryons and the effect of …
View article: Topological terms in abelian lattice field theories
Topological terms in abelian lattice field theories Open
In this contribution we revisit the lattice discretization of the topological charge for abelian lattice field theories. The construction departs from an initially non-compact discretization of the gauge fields and after absorbing 2π shift…
View article: New density of states approaches to finite density lattice QCD
New density of states approaches to finite density lattice QCD Open
We present two new suggestions for density of states (DoS) approaches to finite density lattice QCD. Both proposals are based on the recently developed and successfully tested DoS FFA technique, which is a DoS approach for bosonic systems …
View article: Topological terms in abelian lattice field theories
Topological terms in abelian lattice field theories Open
In this contribution we revisit the lattice discretization of the topological charge for abelian lattice field theories. The construction departs from an initially non-compact discretization of the gauge fields and after absorbing $2π$ shi…
View article: New canonical and grand canonical DoS techniques for finite density lattice QCD
New canonical and grand canonical DoS techniques for finite density lattice QCD Open
We discuss two new DoS approaches for finite density lattice QCD. The paper extends a recent presentation of the new techniques based on Wilson fermions, while here we now discuss and test the case of finite density QCD with staggered ferm…
View article: Baryon bag simulation of QCD in the strong coupling limit
Baryon bag simulation of QCD in the strong coupling limit Open
We explore the possibility of a simulation of strong coupling QCD in terms of so-called baryon bags. In this form the known representation in terms of monomers, dimers and baryon loops is reorganized such that the baryon contributions are …
View article: Symmetries of the light hadron spectrum in high temperature QCD
Symmetries of the light hadron spectrum in high temperature QCD Open
Properties of QCD matter change significantly around the chiral crossover temperature, and the effects on $U(1)_A$ and topological susceptibilities, as well as the meson spectrum have been studied with much care. Baryons and the effect of …
View article: Symmetries of spatial meson correlators in high temperature QCD
Symmetries of spatial meson correlators in high temperature QCD Open
Based on a complete set of $J = 0$ and $J=1$ spatial isovector correlation\nfunctions calculated with $N_F = 2$ domain wall fermions we identify an\nintermediate temperature regime of $T \\sim 220 - 500$ MeV ($1.2T_c$--$2.8T_c$),\nwhere ch…
View article: Topology and index theorem with a generalized Villain lattice action – a test in 2d
Topology and index theorem with a generalized Villain lattice action – a test in 2d Open
View article: Bag representation for composite degrees of freedom in lattice gauge theories with fermions
Bag representation for composite degrees of freedom in lattice gauge theories with fermions Open
We explore new representations for lattice gauge theories with fermions, where the space-time lattice is divided into dynamically fluctuating regions, inside which different types of degrees of freedom are used in the path integral. The fi…
View article: Low temperature condensation and scattering data
Low temperature condensation and scattering data Open
We study $ϕ^4$ lattice field theory at finite chemical potential $μ$ in two and four dimensions, using a worldline representation that overcomes the complex action problem. We compute the particle number at very low temperature as a functi…
View article: The critical endpoint in the 2-d U(1) gauge-Higgs model at topological angle $\theta=\pi$
The critical endpoint in the 2-d U(1) gauge-Higgs model at topological angle $\theta=\pi$ Open
We study 2d U(1) gauge Higgs systems with a $\\theta$-term. For properly\ndiscretizing the topological charge as an integer we introduce a mixed group-\nand algebra-valued discretization (MGA scheme) for the gauge fields, such that\nthe ch…