Density of states

Langfeld, Kurt

doi:10.22323/1.256.0010

Cited by 26 publications

(34 citation statements)

References 29 publications

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“…First-principles studies of this regime are hindered by the sign problem: with chemical potential µ = 0 the euclidean action becomes complex, and can therefore not be used as a probability weight in Monte Carlo simulations, which are the mainstay of lattice gauge theory, the method of choice for first-principles, non-perturbative quantum field theory. Despite recent progress in alternative sampling approaches such as the density of states method [1], complex Langevin [2] and Lefschetz thimble and related approaches [3,4], we do not as yet have any method that has been shown to yield valid and reliable results for real QCD.…”

Section: Introductionmentioning

confidence: 99%

Dense two-color QCD towards continuum and chiral limits

et al. 2020

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We study two-color QCD with two flavors of Wilson fermion as a function of quark chemical potential µ and temperature T , for two different lattice spacings and two different quark masses. We find that the quarkyonic region, where the behaviour of the quark number density and the diquark condensate are described by a Fermi sphere of almost free quarks distorted by a BCS gap, extends to larger chemical potentials with decreasing lattice spacing or quark mass. In both cases, the quark number density also approaches its non-interacting value. The pressure at low temperature is found to approach the Stefan-Boltzmann limit from below.

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Section: Introductionmentioning

confidence: 99%

Dense two-color QCD towards continuum and chiral limits

et al. 2020

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“…Methods tested in the context of lattice gauge theories include e.g. Lefschetz thimbles [2,3], complex Langevin simulations [4,5] and density of states methods [6]. In this paper, we concentrate on the Hamiltonian approach in the framework of tensor networks (TN).…”

Section: Introductionmentioning

confidence: 99%

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

et al. 2019

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Employing matrix product states as an ansatz, we study the non-thermal phase structure of the (1+1)-dimensional massive Thirring model in the sector of vanishing total fermion number with staggered regularization. In this paper, details of the implementation for this project are described. To depict the phase diagram of the model, we examine the entanglement entropy, the fermion bilinear condensate and two types of correlation functions. Our investigation shows the existence of two phases, with one of them being critical and the other gapped. An interesting feature of the phase structure is that the theory with non-zero fermion mass can be conformal. We also find clear numerical evidence that these phases are separated by a transition of the Berezinskii-Kosterlitz-Thouless type. Results presented in this paper establish the possibility of using the matrix product states for probing this type of phase transition in quantum field theories. They can provide information for further exploration of scaling behaviour, and serve as an important ingredient for controlling the continuum extrapolation of the model. arXiv:1908.04536v2 [hep-lat] 21 Aug 2019 1 A different TN approach, the tensor renormalization group method, in which one works with the partition function, has also been implemented for the investigation of several quantum field theories [63-71] and the formulation of quantum gravity [72].

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“…The recent years have seen remarkable advances for simulating those theories: Complexification of fields [14] gave rise to Complex Langevin simulations [15,16] or Lefschetz Thimble inspired methods [17]. Algorithmic advances [18] may generically give reliable results for medium size systems (e.g. [19,20]).…”

Section: Introductionmentioning

confidence: 99%

String-like theory as solution to the sign problem of a finite density gauge theory

Langfeld¹

2019

Proceedings of XIII Quark Confinement and the Hadron Spectrum — PoS(Confinement2018)

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Z3 gauge theory with dynamical (bosonic) matter is studied in 4 dimensions with a finite chemical potential. This theory could be viewed as an effective theory describing the centre vortex picture of QCD colour confinement, but it is studied here with local interactions as theory in its own right. It is shown that the sign-problem can be solved by dualisation. The dual theory is derived: the pure gauge sector is a theory of closed membranes with Nambu-Goto action, and matter is described by open branes bounded by closed matter loops. The brane theory is simulated with Monte-Carlo techniques. Some evidence is found that the theory possesses a weakly-renormalisable phase with the scale set by a mass gap. Deconfinement at low temperatures and finite chemical potentials appears as a percolation transition for matter loops.

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Density of states

Cited by 26 publications

References 29 publications

Dense two-color QCD towards continuum and chiral limits

Dense two-color QCD towards continuum and chiral limits

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

String-like theory as solution to the sign problem of a finite density gauge theory

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