arXiv subjects

Oleg Borisenko

Publications and source records attributed to Oleg Borisenko.

14 recordsLinked to original sources

arXiv2021

Dual Polyakov loop model at finite density: phase diagram and screening masses

We consider a dual representation of an effective three-dimensional Polyakov loop model for the SU(3) theory at nonzero real chemical potential. This representation is free of the sign problem and can be used for numeric Monte-Carlo simulations. These simulations allow us to locate the line of second order phase transitions, that separates the region of first order phase transition from the crossover one. The behavior of local observables in different phases of the model is studied numerically and compared with predictions of the mean-field analysis. Our dual formulation allows us to study also Polyakov loop correlation functions. From these results, we extract the screening masses and compare them with large-N predictions.

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arXiv2021

Dual simulation of a Polyakov loop model at finite baryon density: phase diagram and local observables

Many Polyakov loop models can be written in a dual formulation which is free of sign problem even when a non-vanishing baryon chemical potential is introduced in the action. Here, results of numerical simulations of a dual representation of one such effective Polyakov loop model at finite baryon density are presented. We compute various local observables such as energy density, baryon density, quark condensate and describe in details the phase diagram of the model. The regions of the first order phase transition and the crossover, as well as the line of the second order phase transition, are established. We also compute several correlation functions of the Polyakov loops.

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arXiv2016

BKT phase transitions in two-dimensional non-Abelian spin models

It is argued that two-dimensional U(N) spin models for any N undergo a BKT-like phase transition, similarly to the famous XY model. This conclusion follows from the Berezinskii-like calculation of the two-point correlation function in U(N) models, approximate renormalization group analysis and numerical investigations of the U(2) model. It is shown, via Monte Carlo simulations, that the universality class of the U(2) model coincides with that of the XY model. Moreover, preliminary numerical results point out that two-dimensional SU(N) spin models with the fundamental and adjoint terms and N>4 exhibit two phase transitions of BKT type, similarly to Z(N) vector models.

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arXiv2015

Deconfinement and universality in the 3D U(1) lattice gauge theory at finite temperature: study in the dual formulation

We study analytically and numerically the three-dimensional U(1) lattice gauge theory at finite temperature in the dual formulation. For an appropriate disorder operator, we obtain the renormalization group equations describing the critical behavior of the model in the vicinity of the deconfinement phase transition. These equations are used to check the validity of the Svetitsky-Yaffe conjecture regarding the critical behavior of the lattice U(1) model. Furthermore, we perform numerical simulations of the model for $N_t = 1, 2, 4, 8$ and compute, by a cluster algorithm, the dual correlation functions and the corresponding second moment correlation length. In this way we locate the position of the critical point and calculate critical indices.

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arXiv2014

Critical behavior and continuum scaling of $3D$ $Z(N)$ lattice gauge theories

Three-dimensional $Z(N)$ lattice gauge theories are studied numerically at finite temperature for $N$ = 5, 6, 8, 12, 13, 20 and for $N_t$=2,4,8. For each model the location of phase transitions and its critical indices are determined. The scaling of critical points with $N$ is proposed. The data obtained enable us to verify the scaling near the continuum limit for the $Z(N)$ models at finite temperatures.

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arXiv2014

Phase structure of 3D Z(N) lattice gauge theories at finite temperature: large-N and continuum limits

We study numerically three-dimensional Z(N) lattice gauge theories at finite temperature, for N = 5, 6, 8, 12, 13 and 20 on lattices with temporal extension $N_t$ = 2, 4, 8. For each model, we locate phase transition points and determine critical indices. We propose also the scaling of critical points with N. The data obtained enable us to verify the scaling near the continuum limit for the Z(N) models at finite temperatures.

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arXiv2013

Phase transitions in the three-dimensional Z(N) models

Phase transitions in zero-temperature 3D Z(N) lattice gauge theories are studied. We use a cluster algorithm defined for the dual formulation of the models. We also attempt to explain the nature of the intermediate continuously symmetric phase, which appears for N>5. The critical indices are calculated. The results obtained are used to study the scaling of critical points with N, as well as the scaling of finite-temperature critical points with the lattice size in the time direction, $N_t$.

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arXiv2013

Critical properties of 3D Z(N) lattice gauge theories at finite temperature

The phase structure of three-dimensional Z(N>4) lattice gauge theories at finite temperature is investigated. Using the dual formulation of the models and a cluster algorithm we locate the critical points of the two transitions, determine various critical indices and compute average action and specific heat. Results are consistent with two transitions of infinite order, belonging to the universality class of two-dimensional Z(N) vector spin models.

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arXiv2011

Critical properties of 2D Z(N) vector models for N>4

We investigate the critical properties of two-dimensional Z(N) vector models for N larger than 4. In particular, critical points of the two phase transitions are located and some critical indices are determined. We study also the behavior of the helicity modulus and the dependence of the critical points on N.

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arXiv2011

Numerical study of the phase transitions in the two-dimensional Z(5) vector model

We investigate the critical properties of the two-dimensional Z(5) vector model. For this purpose, we propose a new cluster algorithm, valid for Z(N) models with odd values of N. The two-dimensional Z(5) vector model is conjectured to exhibit two phase transitions with a massless intermediate phase. We locate the position of the critical points and study the critical behavior across both phase transitions in details. In particular, we determine various critical indices and compare the results with analytical predictions.

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arXiv2011

Critical properties of the 2D Z(5) vector model

The two-dimensional Z(5) vector model is investigated through the determination of critical points and one critical index. To this purpose a new cluster algorithm has been developed valid for 2D Z(N) models with odd values of N. Results are compared with analytical predictions.

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arXiv2010

Critical behaviour of the compact 3d U(1) gauge theory at finite temperature

Critical properties of the compact three-dimensional U(1) lattice gauge theory are explored at finite temperatures. The critical point of the deconfinement phase transition, critical indices and the string tension are studied numerically on lattices with temporal extension N_t = 8 and spatial extension ranging from L = 32 to L = 256. The critical indices, which govern the behaviour across the deconfinement phase transition, are generally expected to coincide with the critical indices of the two-dimensional XY model. It is found that the determination of the infinite volume critical point differs from the pseudo-critical coupling at L = 32, found earlier in the literature and implicitly assumed as the onset value of the deconfined phase. The critical index $ν$ computed from the scaling of the pseudocritical couplings agrees well with the value $ν$ = 1/2 of the XY model. The computation of the index $η$ brings to a value larger than expected. The possible reasons for such behaviour are discussed.

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arXiv2010

Critical behavior of the compact 3d U(1) gauge theory on isotropic lattices

We report on the computation of the critical point of the deconfinement phase transition, critical indices and the string tension in the compact three dimensional U(1) lattice gauge theory at finite temperatures. The critical indices govern the behavior across the deconfinement phase transition in the pure gauge U(1) model and are generally expected to coincide with the critical indices of the two-dimensional XY model. We studied numerically the U(1) model for N_t=8 on lattices with spatial extension ranging from L=32 to L=256. Our determination of the infinite volume critical point on the lattice with N_t=8 differs substantially from the pseudo-critical coupling at L=32, found earlier in the literature and implicitly assumed as the onset value of the deconfined phase. The critical index $ν$ computed from the scaling of the pseudo-critical couplings with the extension of the spatial lattice agrees well with the XY value $ν$=1/2. On the other hand, the index $η$ shows large deviation from the expected universal value. The possible reasons of such behavior are discussed in details.

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arXiv2008

Critical behavior of the compact 3d U(1) theory in the limit of zero spatial coupling

Critical properties of the compact three-dimensional U(1) lattice gauge theory are explored at finite temperatures on an asymmetric lattice. For vanishing value of the spatial gauge coupling one obtains an effective two-dimensional spin model which describes the interaction between Polyakov loops. We study numerically the effective spin model for N_t=1,4,8 on lattices with spatial extension ranging from L=64 to L=256. Our results indicate that the finite-temperature U(1) lattice gauge theory belongs to the universality class of the two-dimensional XY model, thus supporting the Svetitsky-Yaffe conjecture.

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