arXiv subjects

O. Borisenko

Publications and source records attributed to O. Borisenko.

At least 37 records · Page 2Linked to original sources

arXiv2013

On a development of the phenomenological renormalization group

We propose a modification of the Nightingale renormalization group for lattice spin and gauge models by combining it with the cluster decimation approximation. Essential ingredients of our approach are: 1) exact calculation of the partition and correlation function on a finite lattice strip; 2) preservation of the mass gap or the second moment correlation length, computed in the infinite strip length limit, on each decimation step. The method is applied for studying general two and three dimensional Z(N) models. A perfect agreement with exact results (whenever available) is found. An extension of the method to models with a continuous symmetry is briefly discussed.

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arXiv2013

Critical behavior of 3D Z(N) lattice gauge theories at zero temperature

Three-dimensional $Z(N)$ lattice gauge theories at zero temperature are studied for various values of $N$. Using a modified phenomenological renormalization group, we explore the critical behavior of the generalized $Z(N)$ model for $N=2,3,4,5,6,8$. Numerical computations are used to simulate vector models for $N=2,3,4,5,6,8,13,20$ for lattices with linear extension up to $L=96$. We locate the critical points of phase transitions and establish their scaling with $N$. The values of the critical indices indicate that the models with $N>4$ belong to the universality class of the three-dimensional $XY$ model. However, the exponent $α$ derived from the heat capacity is consistent with the Ising universality class. We discuss a possible resolution of this puzzle. We also demonstrate the existence of a rotationally symmetric region within the ordered phase for all $N\geq 5$ at least in the finite volume.

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arXiv2012

Phase structure of 3D Z(N) lattice gauge theories at finite temperature

We perform a numerical study of the phase transitions in three-dimensional Z(N) lattice gauge theories at finite temperature for N>4. Using the dual formulation of the models and a cluster algorithm 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, compute the average action and the specific heat. Our results are consistent with the two transitions being of infinite order. Furthermore, they belong to the universality class of two-dimensional Z(N) vector spin models.

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arXiv2012

BKT phase transitions in strongly coupled 3D Z(N) LGT at finite temperature

We investigate, both analytically and numerically, the phase diagram of three-dimensional Z(N) lattice gauge theories at finite temperature for N > 4. These models, in the strong coupling limit, are equivalent to a generalized version of vector Potts models in two dimension, with Polyakov loops playing the role of Z(N) spins. It is argued that the effective spin models have two phase transitions of infinite order (i.e. BKT). Using a cluster algorithm we confirm this conjecture, locate the position of the critical points and extract various critical indices.

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arXiv2012

Phase transitions in strongly coupled 3d Z(N) lattice gauge theories at finite temperature

We perform an analytical and numerical study of the phase transitions in three-dimensional Z(N) lattice gauge theories at finite temperature for N>4 exploiting equivalence of these models with a generalized version of the two-dimensional vector Potts models in the limit of vanishing spatial coupling. In this limit the Polyakov loops play the role of Z(N) spins. The effective couplings of these two-dimensional spin models are calculated explicitly. It is argued that the effective spin models have two phase transitions of BKT type. This is confirmed by large-scale Monte Carlo simulations. Using a cluster algorithm 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, compute the helicity modulus, the average action and the specific heat. A scaling formula for the critical points with N is proposed.

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arXiv2012

The phase transitions in 2D Z(N) vector models for N>4

We investigate both analytically and numerically the renormalization group equations in 2D Z(N) vector models. The position of the critical points of the two phase transitions for N>4 is established and the critical index ν is computed. For N=7, 17 the critical points are located by Monte Carlo simulations and some of the corresponding critical indices are determined. The behavior of the helicity modulus is studied for N=5, 7, 17. Using these and other available Monte Carlo data we discuss the scaling of the critical points with N and some other open theoretical problems.

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arXiv2011

Monopoles in the Plaquette Formulation of the 3D SU(2) Lattice Gauge Theory

Using a plaquette formulation for lattice gauge models we describe monopoles of the three dimensional SU(2) theory which appear as configurations in the complete axial gauge and violate the continuum Bianchi identity. Furthemore we derive a dual formulation for the Wilson loop in arbitrary representation and calculate the form of the interaction between generated electric flux and monopoles in the region of a weak coupling relevant for the continuum limit. The effective theory which controls the interaction is of the sine-Gordon type model. The string tension is calculated within the semiclassical approximation.

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arXiv2005

Plaquette representation for 3D lattice gauge models: I. Formulation and perturbation theory

We develop an analytical approach for studying lattice gauge theories within the plaquette representation where the plaquette matrices play the role of the fundamental degrees of freedom. We start from the original Batrouni formulation and show how it can be modified in such a way that each non-abelian Bianchi identity contains only two connectors instead of four. In addition, we include dynamical fermions in the plaquette formulation. Using this representation we construct the low-temperature perturbative expansion for U(1) and SU(N) models and discuss its uniformity in the volume. The final aim of this study is to give a mathematical background for working with non-abelian models in the plaquette formulation.

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arXiv2004

Dual formulations of non-abelian spin models: local representation and low-temperature asymptotics

Non-abelian lattice spin models with symmetry group SU(N) or U(N) can be formulated in terms of link variables which are subject to the Bianchi constraints. Using this representation we derive exact and local dual formulation for the partition function of such models on a cubic lattice in arbitrary dimension D. Locality means that the dual action is given by a sum over some subset of hypercubes of the dual lattice and the interaction between dual variables ranges over one given hypercube. Dual variables are in general discrete-valued and live on (D-2)-cell of the dual lattice, in close analogy with the XY model. We use our construction to study in details the dual of SU(2) principal chiral model in two dimensions. We give dual expressions also for two-point correlation function in arbitrary representation and for the free energy of defects. Leading terms of the asymptotic expansion of the dual Boltzmann factor are computed and it is proven that at low temperatures it converges to a certain Gaussian distribution uniformly in all fluctuations of dual variables. This result enables us to define the semiclassical limit of the dual formulation and to determine an analog of the vortex--spin-wave representation for the partition function. Such representation is used to extract leading perturbative contribution to the correlation function which shows power-like decay at weak coupling. We also present some analytical evidences that the low-temperature limit of the dual formulation is completely described by ISO(2)-like approximation of SU(2) matrix elements.

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arXiv2002

Analytical study of low temperature phase of 3D LGT in the plaquette formulation

We develop an analytical approach for non-abelian gauge models within the plaquette representation where the plaquette matrices play the role of the fundamental degrees of freedom. We start from the original Batrouni formulation and show how it can be modified in such a way that each non-abelian Bianchi identity contains two connectors instead of four. Using this representation we construct the low-temperature expansion for U(1) and SU(N) models on a finite lattice and discuss its uniformity in the volume. Next, we derive a dual representation for the 't Hooft loop in the SU(2) model and describe monopoles in the maximal axial gauge.

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arXiv1999

Exponential corrections to low-temperature expansion of 2D non-abelian models

The thermodynamic limit of certain exponential corrections to the weak coupling expansion of two-dimensional models is investigated. The expectation values of operators contributing to the first order coefficient of the low-temperature expansion of the free energy are calculated for the order O(e^{-β}). They are proven to diverge logarithmically with the volume for non-abelian models.

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arXiv1999

Low-temperature expansion in link formulation. II

We extend our previous analysis to arbitrary two dimensional SU(N) principal chiral model in a link formulation. A general expression for the second order coefficient of fixed distance correlation function is given in terms of Green functions. This coefficient is calculated for distance 1 and is proven to be path independent. We also study the weak coupling expansion of the free energy of one dimensional SU(N) model and explain why it is non-uniform in the volume. Further, we investigate the contribution of holonomy operators to the low-temperature expansion in two dimensions. All our results agree with the conventional expansion. Nevertheless, we give some example which indicates that the expansion in the link formulation can also suffer from ambiguities previously found in the conventional perturbation theory.

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arXiv1999

Low-temperature expansion and perturbation theory in 2D models with unbroken symmetry: a new approach

A new method of constructing a weak coupling expansion of two dimensional (2D) models with an unbroken continuous symmetry is developed. The method is based on an analogy with the abelian XY model, respects the Mermin-Wagner (MW) theorem and uses a link representation of the partition and correlation functions. An expansion of the free energy and of the correlation functions at small temperatures is performed and first order coefficients are calculated explicitly. They are shown to coincide with the results of the conventional perturbation theory. We discuss an applicability of our method to analysis of uniformity of the low-temperature expansion.

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arXiv1999

On the Deconfinement Phase Transition in Hot Gauge Theories with Dynamical Matter Fields

The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. Since this ensemble implies a projection to the zero triality sector of the theory we introduce a proper quantity which is able to reveal a critical behaviour of the theory with fundamental quarks. We discuss the properties of both the chromoelectric and chromomagnetic sectors of the theory and show while electric charges carrying a unit of Z(N) charge are screened at high temperatures by dynamical matter loops, this is not the case for the Z(N) magnetic flux. An order parameter is constructed to probe the realization of local discrete Z(N) symmetry in the magnetic sector. We argue it can be used to detect a deconfinement phase being defined in terms of the screening mechanism as a phase of unscreened Z(N) flux. It may be detectable at long range via the Aharonov-Bohm effect. We discuss the possible phase structure of QCD in this approach.

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arXiv1999

Running Coupling in the SU(2) Lattice Gauge Theory

Scenario according to which the SU(2)-gluodynamics is a theory with a nontrivial fixed point is analyzed from the point of view of the modern Monte-Carlo (MC) lattice data. It is found that an assumption of the first order fixed point g=g_f of the beta function has no contradictions with existing MC lattice data. The beta function parameters are found from the requirement of constant values for critical temperature and string tension in MC lattice calculations at 4/g^2 >= 2.30.

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arXiv1998

May vortices produce a mass gap in 2D spin models at weak coupling

We consider the 2D SU(N) principal chiral model and discuss a vortex condensation mechanism which could explain the existence of a non-zero mass gap at arbitrarily small values of the coupling constant. The mechanism is an analogue of the vortex condensation mechanism of confinement in 4D non-Abelian gauge theories. We formulate a sufficient condition for the mass gap to be non-vanishing in terms of the behaviour of the vortex free energy. The SU(2) model is studied in detail. In one dimension we calculate the vortex free energy exactly. An effective model for the center variables of the spin configurations of the 2D SU(2) model is proposed and the Z(2) correlation function is derived in this model. We define a Z(2) mass gap in both the full and effective model and argue that they should coincide whenever the genuine mass gap is non-zero. We show via Monte-Carlo simulations of the SU(2) model that the Z(2) mass gap reproduces the full mass gap with perfect accuracy. We also test this mechanism in the positive link model which is an analogue of the positive plaquette model in gauge theories and find excellent agreement between the full and the Z(2) mass gap.

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arXiv1998

On weak coupling expansion in models with unbroken symmetry

An investigation of the weak coupling region of 2D SU(N) spin models is presented. An expansion of the free energy and correlation functions at low temperatures is performed in the link formulation with periodic boundary conditions (BC). The resulting asymptotics is shown to be nonuniform in the volume for the free energy.

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arXiv1997

Towards the Deconfinement Phase Transition in Hot Gauge Theories

The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. We discuss properties of chromoelectric and chromomagnetic sectors of the theory and show whereas electric charges carrying a unit of Z(N) charge are screened at high temperatures via dynamical matter loops, this is not the case for the Z(N) magnetic flux. An order parameter is constructed to probe the realization of local Z(N) symmetry in the magnetic sector. We argue this order parameter may be used to detect the deconfinement phase transition which is defined in terms of the screening mechanism.

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