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V. K. Mitrjushkin

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

At least 37 records · Page 2Linked to original sources
arXiv2006

Landau gauge ghost and gluon propagators in SU(2) lattice gauge theory: Gribov ambiguity revisited

We reinvestigate the problem of Gribov ambiguities within the Landau (or Lorentz) gauge for the ghost and gluon propagators in pure SU(2) lattice gauge theory. We make use of the full symmetry group of the action taking into account {\it large}, i.e. non-periodic $\mathbb{Z}(2)$ gauge transformations leaving lattice plaquettes invariant. Enlarging in this way the gauge orbits for any given gauge field configuration the Landau gauge can be fixed at higher local extrema of the gauge functional in comparison with standard (overrelaxation) techniques. This has a clearly visible effect not only for the ghost propagator at small momenta but also for the gluon propagator, in contrast to the common belief.

hep-lat↗
arXiv2004

On practical problems to compute the ghost propagator in SU(2) lattice gauge theory

In SU(2) lattice pure gauge theory we study numerically the dependence of the ghost propagator G(p) on the choice of Gribov copies in Lorentz (or Landau) gauge. We find that the effect of Gribov copies is essential in the scaling window region, however, it tends to decrease with increasing beta. On the other hand, we find that at larger beta-values very strong fluctuations appear which can make problematic the calculation of the ghost propagator.

hep-lat↗
arXiv2003

On the gauge dependence of the singlet and adjoint potentials

We study gauge dependence of the recently suggested definition of the singlet and adjoint potentials in SU(2) lattice gauge theory. We find that in the (time local) maximal tree axial gauge the singlet potential obtained from the gauge dependent correlator ${Tr} L(x)L^\dagger(y)$ differs from that computed in the Coulomb gauge. In the generalized Coulomb gauge we find the range of the parameter values in which the singlet potential differs from that in the Coulomb gauge.

hep-lat↗
arXiv2002

Currents, chemical potential and boundary conditions in lattice QCD

A connection between the operator fermionic currents $\hatJ$ and corresponding `Grassmannian' currents $J$ in the functional integral formalism is studied. The QCD action with non--zero chemical potential $μ$ is derived. A connection between the fermionic Fock space and boundary conditions along the forth direction is discussed.

hep-lat↗
arXiv2002

Transfer matrix and nonperturbative renormalization of fermionic currents in lattice QCD

The functional integral representation for fermionic observables on the lattice is studied. In particular, Grassmannian representations of the scalar $\hatJ^{(S)}$ and pseudoscalar $\hatJ^{(P)}$ currents and pseudoscalar correlator are derived. It is also discussed the connection between the fermionic Fock space and boundary conditions along the time direction.

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arXiv2002

Gluon propagators and the choice of the gauge field in SU(2) theory on the lattice

We study numerically magnetic $G_M(p)$ and electric $G_E(p)$ gluon propagators and their dependence on the choice of the lattice gauge field $\caa_{xμ}$ in SU(2) gauge theory, especially, in the low--momentum limit. We find that two different $\caa_{xμ}$ definitions are equivalent up to a trivial renormalization of the propagator, at least, in the main approximation.

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arXiv2001

Performance studies of the two-step multiboson algorithm in compact lattice QED

The performance of the two-step multiboson (TSMB) algorithm is investigated in comparison with the hybrid Monte Carlo (HMC) method for compact lattice QED with standard Wilson fermions both in the Coulomb and confinement phases. The restriction to QED allows for extensive measurements of autocorrelation times. Preliminary results show that the TSMB algorithm is at least competitive with standard HMC.

hep-lat↗
arXiv2001

PJLZ--gauge fixing approach in SU(2) lattice gauge theory

We study the SU(2) gauge theory with the interpolating gauge {\it a la} Parrinello--Jona-Lasinio--Zwanziger (PJLZ) with the gauge fixing functional $F=\sum_{xμ} {1/2}\tr (U_{xμ}σ_3U_{xμ}^{\dagger}σ_3)$. We find a strong indication of the non--analiticity with respect to the interpolating parameter $λ$ at $λ_c \sim 0.8$.

hep-lat↗
arXiv2000

Zero-momentum modes and chiral limit in compact lattice QED

The influence of zero-momentum gauge modes on physical observables is investigated for compact lattice QED with dynamical and quenched Wilson fermions. Within the Coulomb phase, zero-momentum modes are shown to hide the critical behaviour of gauge invariant fermion observables near the chiral limit. Methods for eliminating zero-momentum modes are discussed.

hep-lat↗
arXiv2000

Compact fields and mass generation

It is shown that the free propagator of an angular, i.e. compact, field with zero lagrangian mass acquires a nonzero propagator mass $ω$ (`kinematical' mass generation). To demonstrate this effect the free propagator of the goldstone boson in an O(2) model with spontaneous symmetry breaking is calculated. It is shown that this propagator is massive, the mass $ω$ being a function of the scalar `condensate' ${\barϕ}$.

hep-lat↗
arXiv2000

Lorentz gauge fixing and lattice QED

The Gribov ambiguity problem is studied for compact lattice QED within the Lorentz gauge. In the Coulomb phase, Gribov copies are mainly caused by double Dirac sheets and zero-momentum modes of the gauge fields. Removing them by (non-) periodic gauge transformations allows to reach the absolute extremum of the Lorentz gauge functional. For standard Lorentz gauge fixing the Wilson fermion correlator turns out to be strongly effected by the zero-momentum modes. A reliable fermion mass estimate requires the proper treatment of these modes.

hep-lat↗
arXiv1999

Fermionic correlators and zero-momentum modes in quenched lattice QED

For the Lorentz gauge the influence of various Gribov gauge copies on the fermion propagator is investigated in quenched compact lattice QED. Within the Coulomb phase besides double Dirac sheets the zero-momentum modes of the gauge fields are shown to cause the propagator to deviate strongly from the perturbatively expected behaviour. The standard way to extract the fermion mass fails. The recently proposed zero-momentum Lorentz gauge is demonstrated to cure the problem.

hep-lat↗
arXiv1999

Lorentz gauge and Gribov ambiguity in the compact lattice U(1) theory

The Gribov ambiguity problem is studied for compact U(1) lattice theory within the Lorentz gauge. In the Coulomb phase, it is shown that apart from double Dirac sheets all gauge (i.e. Gribov) copies originate mainly from the zero-momentum modes of the gauge fields. The removal of the zero-momentum modes turns out to be necessary for reaching the absolute maximum of the gauge functional $F(θ)$. A new gauge fixing procedure - zero-momentum Lorentz gauge - is proposed.

hep-lat↗
arXiv1999

Gribov copies and gauge variant correlators in U(1) lattice gauge theory

We discuss the influence of Dirac sheets and zero-momentum modes on the gauge variant photon correlators $Γ(τ;\vp)$ with $\vp\ne 0$ and $\vp =0$ in the pure gauge U(1) theory. A special attention has been paid to the $β$- and volume-dependence of this influence. Numerical simulations are performed on $12\times 6^3$ and $24\times 12^3$ lattices at different $yβ$'s in the Coulomb phase.

hep-lat↗
arXiv1998

Passing through the `chiral limit' in quenched QCD with Wilson fermions

We investigate the limit of vanishing quark mass in quenched lattice QCD with unimproved Wilson fermions at $β=6.0$. Exploiting the correlations of propagators at different time slices we extract pion masses extremely close to the `chiral limit', despite the presence of `exceptional configurations'. With this at hand, the existence of quenched chiral logarithms can be demonstrated, provided, finite size effects are small. With reference to the phase diagram proposed by Aoki also the range $κ> κ_c$ is investigated. The width of a potential parity-flavor violating phase can, if at all, hardly be resolved.

hep-lat↗
arXiv1998

Gluon propagator and zero-momentum modes in SU(2) lattice gauge theory

We investigate propagators in Lorentz (or Landau) gauge by Monte Carlo simulations. In order to be able to compare with perturbative calculations we use large $β$ values. There the breaking of the Z(2) symmetry turns out to be important for all of the four lattice directions. Therefore we make sure that the analysis is performed in the correct state. We discus implications of the gauge fixing mechanism and point out the form of the weak-coupling behavior to be expected in the presence of zero-momentum modes. Our numerical result is that the gluon propagator in the weak-coupling limit is strongly affected by zero-momentum modes. This is corroborated in detail by our quantitative comparison with analytical calculations.

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