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V. K. Petrov

Publications and source records attributed to V. K. Petrov.

18 recordsLinked to original sources

Physical properties of Polyakov loop geometrical clusters in SU(2) gluodynamics

We apply the liquid droplet model to describe the clustering phenomenon in SU(2) gluodynamics, especially, in the vicinity of the deconfinement phase transition. In particular, we analyze the size distributions of clusters formed by the Polyakov loops of the same sign. Within such an approach this phase transition can be considered as the transition between two types of liquids where one of the liquids (the largest droplet of a certain Polyakov loop sign) experiences a condensation, while the other one (the next to largest droplet of opposite Polyakov loop sign) evaporates. The clusters of smaller sizes form two accompanying gases, and their size distributions are described by the liquid droplet parameterization. By fitting the lattice data we have extracted the value of Fisher exponent $τ=$ 1.806 $\pm$ 0.008. Also we found that the temperature dependences of the surface tension of both gaseous clusters are entirely different below and above the phase transition and, hence, they can serve as an order parameter. The critical exponents of the surface tension coefficient in the vicinity of the phase transition are found. Our analysis shows that the temperature dependence of the surface tension coefficient above the critical temperature has a $T^2$ behavior in one gas of clusters and $T^4$ in the other one.

hep-lat↗

Quark Gluon Bags as Reggeons

The influence of the medium dependent finite width of QGP bags on their equation of state is analyzed within an exactly solvable model. It is argued that the large width of the QGP bags not only explains the observed deficit in the number of hadronic resonances, but also clarifies the reason why the heavy QGP bags cannot be directly observed as metastable states in a hadronic phase. The model allows us to estimate the minimal value of the width of QGP bags from a variety of the lattice QCD data and get that the minimal resonance width at zero temperature is about 600 MeV, whereas the minimal resonance width at the Hagedorn temperature is about 2000 MeV. As shown these estimates are almost insensitive to the number of the elementary degrees of freedom. The recent lattice QCD data are analyzed and it is found that besides sigma T**4 term the lattice QCD pressure contains T-linear and T**4 ln T terms in the range of temperatures between 240 MeV and 420 MeV. The presence of the last term in the pressure bears almost no effect on the width estimates. Our analysis shows that at hight temperatures the average mass and width of the QGP bags behave in accordance with the upper bound of the Regge trajectory asymptotics (the linear asymptotics), whereas at low temperatures they obey the lower bound of the Regge trajectory asymptotics (the square root one). Since the model explicitly contains the Hagedorn mass spectrum, it allows us to remove an existing contradiction between the finite number of hadronic Regge families and the Hagedorn idea of the exponentially growing mass spectrum of hadronic bags.

hep-ph↗

Exploring an Origin of the QCD Critical Endpoint

We discuss a new way to develop the exactly solvable model of the QCD critical endpoint by matching the deconfinement phase transition line for the system of quark-gluon bags with the line of their vanishing surface tension coefficient. In contrast to all previous findings in such models the deconfined phase is defined not by an essential singularity of the isobaric partition function, but by its simple pole. As a result we find out that the first order deconfinement phase transition which is defined by a discontinuity of the first derivative of system pressure is generated by a discontinuity of the derivative of surface tension coefficient.

hep-ph↗

Why Don't We See the Hagedorn Mass Spectrum in the Experiments?

The influence of medium dependent finite width of the QGP bags on their equation of state is analyzed on a basis of an exactly solvable model with the general mass-volume spectrum of these bags. It is arguing that the consistent statistical description of the QGP bags is achieved for the width proportional to the square root of their volume. The model allows us to estimate the minimal value of the QGP bags' width from the new lattice QCD data. The large width of the QGP bags not only explains the observed deficit in the number of hadronic resonances compared to the Hagedorn mass spectrum, but also clarifies the reason why the heavy/ large QGP bags cannot be directly observed in experiments as metastable states in a hadronic phase.

hep-ph↗

Fresh look at the Hagedorn mass spectrum as seen in the experiments

The medium dependent finite width is introduced into an exactly solvable model with the general mass-volume spectrum of the QGP bags. The model allows us to estimate the minimal value of the QGP bags' width from the lattice QCD data. The large width of the QGP bags not only explains the observed deficit in the number of hadronic resonances comparing to the Hagedorn mass spectrum, but also clarifies the reason why the heavy QGP bags cannot be directly observed as metastable states in a hadronic phase.

nucl-th↗

Asymptotic transition from Fourier series to integrals in LGT

It is shown that in asymptotic transition from Fourier series to integrals an error and ambiguity may arise. Ambiguity reduces to a possibility of addition of some distribution to the result. Properties of such distributions are studied and conditions are established under which ambiguity doesn't arise. Method for correction computation is suggested and conditions for correction turning to zero are specified.

hep-lat↗

Random membrane model for lattice gluodynamics

odel for studying coupling dependence on lattice spacing a in gluodynamics is suggested. The model predicts $g-> g_{0}>0 with a->0. Free energy density in the model does not depend on temperature.

hep-lat↗

A Probabilistic Model of Machine Translation

A probabilistic model for computer-based generation of a machine translation system on the basis of English-Russian parallel text corpora is suggested. The model is trained using parallel text corpora with pre-aligned source and target sentences. The training of the model results in a bilingual dictionary of words and "word blocks" with relevant translation probability.

cs.CL↗

Potential between adjoint sources in arbitrary representations

The potential between sources in arbitrary representations of the gauge group is studied on an anisotropic lattice in a spherical model approximation. It is shown analytically that for half-integer $j$ and $j'$ in the confinement phase the potential rises linearly, whereas for integer $j$ and half-integer $j'$ it rises infinitely which means a strong suppression of the combination of such states . For integer $j$ and $j'$ the potential shows Debay screening and Coulomb behavior in the deconfinement phase >. It is also shown, that $<χ^{(j)}> \backsim <χ>^{2j}$ when $<χ> \gtrsim1$ and is in agreement with the mean field theory prediction, and $<χ^{(j)}> \backsim <χ>$ for $<χ> \lesssim1$ which agrees with MC experiment. String tension model-computed for sources invariant under center group transformations demonstrates Casimir scaling in the intermediate distance regime and turns into zero at large distances.

hep-lat↗

Scaling in a toy model of gluodynamics at finite temperatures

In the limit of $ξ\simeq a_σ/a_τ\to \infty $ the gluodynamics without the magnetic part of action ($S_M\sim 1/ξ$) is considered as a self-contained model. The model is studied analytically in the continuum limit on an extremely large lattice ($N_τ\to \infty $). Scaling conditions for critical temperature and string tension are considered. The model shows trivial ($g^2\sim a_τ$) asymptotic freedom in the case of continuous gauge groups and nontrivial one ($g^2\sim 1/\ln 1/a_τ$) for discrete groups.

hep-lat↗

Asymmetry Parameter Role in Description of Phase Structure of Lattice Gluodynamics at Finite Temperature

The role of lattice asymmetry parameter in description of the SU(2) gluodynamics phase structure at finite temperature is studied analytically. The fact that renormalization group relations which permit to remove the lattice asymmetry parameter from the thermodynamical quantities in the "naive" limit don't do the same in the approximation SU(N) = Z(N) keeping the "naive" limit results at the same time was point out. An additional condition which would fix asymmetry parameter is needed for this dependence removal.

hep-lat↗

Phase structure and confinement properties of noncompact gauge theories II. Z(N) Wilson loop and effective noncompact model

An approach to studying lattice gauge models in the weak coupling region is proposed. Conceptually, it is based on the crucial role of the original Z(N) symmetry and the invariant gauge group measure. As an example, we calculate an effective model from the compact Wilson formulation of the SU(2) gauge theory in $d=3D3$ dimensions at zero temperature. Confining properties and phase structure of the effective model are studied in details.

hep-lat↗

Phase structure and confinement properties of noncompact gauge theories I

In the context of reviewing noncompact lattice gauge models at zero and finite temperature we study in detail a contribution of the invariant measure and the time-like plaquette configurations to correlation functions, analyze the problem of the compactness of the potentials in respect to the confinement and indicate the essential features to deal with the Wilson gauge theory in the weak coupling region. A method for calculating an effective confining noncompact model is also proposed.

hep-lat↗

Induced Chern-Simons term in lattice QCD at finite temperature

The general conditions for the Chern-Simons action to be induced as a nonuniversal contribution of fermionic determinant are formulated in the finite temperature lattice QCD. The dependence of the corresponding action coefficient on nonuniversal parameters (chemical potentials, vacuum features, etc. ) is explored. Special attention is paid to the role of $A_0$-condensate if it is available in this theory.

hep-lat↗