arXiv subjects

Z. V. Khaidukov

Publications and source records attributed to Z. V. Khaidukov.

15 recordsLinked to original sources

arXiv2024

Colour-electric and colour-magnetic confinement

The basic properties of the confinement mechanism in QCD -- the temperature dependence of the spatial and temporal string tensions ($σ_s(T)$ and $σ_E(T)$) -- are studied in the framework of the Field Correlator Method (FCM). It is shown that both functions are connected respectively to the spatial and temporal parts of the vacuum gluon energy $ε_s$ and $ε_E$ which define their equal values at $T=0$. However at $T>0$ the spatial part is growing with $T$ while the temporal part is destroyed by the hadronic pressure at $T=T_c$ (the deconfinement). Both properties are derived within the same method and are in a good agreement with the corresponding lattice data.

hep-ph↗

arXiv2023

The spatial string tension from the Field Correlator Method

The phenomenon of the almost linear growth of the square root of spatial string tension $\sqrt{σ_s(T)}= c_σ g^2 T$ was found both in lattice and in theory, based on the Field Correlator Method (FCM). In the latter the string tension (both spatial and colorelectric) is expressed as an integral of the two gluon Green's function calculated with the same string tension: $σ= \int G^{(2g)}_σ$. This relation allows to check the selfconsistency of the theory. However at nonzero temperature $T$ in the two-gluon Green's function in the space-like region appear terms which create in $σ_s$ quadratic in T behavior. We calculate below in the paper the $σ_s$ numerically in the whole temperature region $T_c< T < 5 T_c$ using the FCM method and compare the results with lattice data finding a good agreement. This justifies the use of the FCM in the space-like region and in high T thermodynamics without extra parameters.

hep-lat↗

arXiv2022

Chiral Separation Effect vs. Chiral Anomaly

We study relation between Chiral Separation Effect (CSE) and Chiral Anomaly, and argue that CSE does not inherit the immutability of Chiral Anomaly. For QED in the leading order in electric charge, with point-splitting regularization in real-time formalism, we demontrate, in regularization-dependent way though, that CSE is an infrared (IR) effect, while the Anomaly is an ultra-violet (UV) phenomena. Thus, CSE in general is sensitive to non-perturbative interactions that alter the theory IR properties, while the Anomaly is fixed by Lorentz symmetry. The simplest example of such an interaction is the Yukawa-like fermion mass.

hep-ph↗

arXiv2021

Chiral separation effect for spin 3/2 fermions

Chiral Separation Effect (CSE) for systems that feature spin 3/2 fermions was considered. For the self-consistent Adler's model with relativistic massless Rarita-Schwinger fermions (RSA model), we found that the CSE conductivity is five times larger than for massless Dirac fermions. For a model of four-fold band crossing in Rarita-Schwinger-Weyl semimetals, in which massless fermions with quasispin 3/2 exist, we calculated that the CSE conductivity is four times larger than for Weyl fermions. We show that CSE conductivity for any multi-degenerate Fermi point in topological semimetals is proportional to its Chern number and is topologically protected. Along the calculations, we proved an index theorem that relates Chern number of a Fermi-point and spectral asymmetry of the corresponding Landau band structure. The assumption that CSE for any system of chiral fermions is dictated by the corresponding Chern number is found to be correct for RSA model (and for the Dirac fermions).

hep-ph↗

arXiv2021

Chiral Separation Effect in lattice regularization

We consider Chiral Separation Effect (CSE) in the lattice regularized quantum field theory. We discuss two types of regularization - with and without exact chiral symmetry. In the latter case this effect is described by its conventional expression for the massless fermions. This is illustrated by the two particular cases - of Wilson fermions and of the conventional overlap fermions. At the same time in the presence of the exact chiral symmetry the CSE disappears. This is illustrated by the naive lattice fermions, when the contributions of the fermion doublers cancel each other. Another example is the modified version of the overlap regularization proposed recently, where there is the exact chiral symmetry, but as a price for this the fermion doublers become zeros of the Green function. In this case the contribution to the CSE of zeros and poles of the Green function cancel each other.

hep-lat↗

arXiv2021

Anomalous transport phenomena and momentum space topology

Using the derivative expansion applied to the Wigner transform of the two - point Green function this is possible to derive the response of various nondissipative currents to the external gauge fields. The corresponding currents are proportional to the momentum space topological invariants. This allows to analyse systematically various anomalous transport phenomena including the anomalous quantum Hall effect and the chiral separation effect. We discuss the application of this methodology both to the solid state physics and to the high energy physics.

hep-ph↗

arXiv2021

Momentum Space Topology and Non-Dissipative Currents

Relativistic heavy ion collisions represent an arena for the probe of various anomalous transport effects. Those effects, in turn, reveal the correspondence between the solid state physics and the high energy physics, which share the common formalism of quantum field theory. It may be shown that for the wide range of {field-theoretic} models, the response of various nondissipative currents to the external gauge fields is determined by the momentum space topological invariants. Thus, the anomalous transport appears to be related to the investigation of momentum space topology -- the approach developed earlier mainly in the condensed matter theory. Within this methodology we analyse systematically the anomalous transport phenomena, which include, in particular, the anomalous quantum Hall effect, the chiral separation effect, the chiral magnetic effect, the chiral vortical effect and the rotational Hall effect.

hep-ph↗

arXiv2020

Quark-gluon plasma speed of sound in magnetic field

A non-perturbative method of Field Correlators (FCM) is applied to study speed of sound in quark-gluon plasma at temperatures above the deconfinement transition 1 0.5 GeV^2. At large temperatures, the speed of sound tends to the conformal limit; low-temperature behavior demonstrates inverse magnetic catalysis. The effect of magnetic field on the speed of sound in quark-gluon plasma is found to be negligible in any existing Heavy Ion Collision experiment, including \sqrt{s_{NN}}=5.02 TeV Pb-Pb collisions at LHC.

hep-ph↗

arXiv2019

Dynamics of the Polyakov loops in QCD

A non-perturbative method of Field Correlators is applied to calculate the Polyakov loop dependence on temperature, $L(T)$, in the 2+1 flavor QCD with small quark masses, so the only relevant scale is the color-electric string tension $σ(T)$. Polyakov loop in the temperature range 100 MeV $\lesssim T\lesssim$ 400 MeV is expressed via the heavy-light meson mass that decreases with $T$ as $\sqrt{σ(T)}$. The latter is deduced from a gradually vanishing chiral condensate. The resulting $L(T)$ is in good agreement with recent lattice data.

hep-ph↗

arXiv2018

Chiral torsional effect

We propose the new nondissipative transport effect - the appearance of axial current of thermal quasiparticles in the presence of background gravity with torsion. For the non-interacting model of massless Dirac fermions the response of the axial current to torsion is derived. The chiral vortical effect appears to be the particular case of the chiral torsional effect. The proposed effect may be observed in the condensed matter systems with emergent relativistic invariance (Weyl/Dirac semimetals and the $^3$He-A superfluid).

cond-mat.mes-hall↗

arXiv2018

Anatomy of the chiral vortical effect

We consider the system of relativistic rotating fermions in the presence of rotation. The rotation is set up as an enhancement of the angular momentum. In this approach the angular velocity for the angular momentum plays the same role as the chemical potential for density. We calculate the axial current using the direct solutions of the Dirac equation with the MIT bag boundary conditions. Next, we consider the alternative way of the rotation description, in which the local velocity of the substance multiplied by the chemical potential serves as the effective gauge field. In this approach this is possible to relate the axial current of the chiral vortical effect for the massless fermions to the topological invariant in momentum space, which is robust to the introduction of interactions. We compare the results for the axial current obtained using the two above mentioned approaches.

hep-ph↗

arXiv2017

Modified top quark condensation model with the extra heavy fermion, the $125$ GeV Pseudo - Goldstone boson, and the additional heavy scalar bosons

We discuss the modified top quark condensation model proposed in \cite{VZ2015}. This construction was inspired by the top - seesaw scenario, in which the extra heavy fermion $χ$ is added that may be paired with the top quark. Besides, this model incorporates the ideas of the Little Higgs scenario, in which the $125$ GeV scalar particle appears as a Pseudo - Goldstone boson. This model admits (in addition to the $125$ GeV scalar boson $H$) the heavier scalar excitation $H^\prime$. We consider the region of parameters, where its mass is $M_{H^\prime} \sim 1$ TeV, the width of $H^\prime$ is $Γ_{H^\prime} \sim 0.3 M_{H^\prime}$, while the mass of the heavy fermion is $m_χ\sim 1$ TeV. We find that in this model the value of the cross - section $σ_{pp \to H^\prime + X \to γ+γ+ X}$ for $\sqrt{s}=13$ TeV is essentially smaller than the present experimental upper bound. Besides, we find, that for the chosen values of parameters there should exist the CP - even scalar boson with mass $\approx 2 m_χ$ and very small width. In addition, the model predicts the existence of the extra neutral CP even scalar boson and the charged scalar boson with masses of the order of $1$ TeV.

hep-ph↗

arXiv2016

Landau Levels in graphene in the presence of emergent gravity

We consider graphene in the presence of external magnetic field and elastic deformations that cause emergent magnetic field. The total magnetic field results in the appearance of Landau levels in the spectrum of quasiparticles. In addition, the quasiparticles in graphene experience the emergent gravity. We consider the particular choice of elastic deformation, which gives constant emergent magnetic field and vanishing torsion. Emergent gravity may be considered as perturbation. We demonstrate that the corresponding first order approximation affects the energies of the Landau levels only through the constant renormalization of Fermi velocity. The degeneracy of each Landau level receives correction, which depends essentially on the geometry of the sample. There is the limiting case of the considered elastic deformation, that corresponds to the uniformly stretched graphene. In this case in the presence of the external magnetic field the degeneracies of the Landau levels remain unchanged.

cond-mat.mes-hall↗

arXiv2013

On Magnetostatics of Chiral Media

We consider magnetostatics of chiral media with a non-vanishing chiral chemical potential $μ_5\neq 0$. The chiral anomaly is known to have macroscopic manifestations which go beyond the standard classical electrodynamics and we introduce an effective action which accounts for the effect of the anomaly. A new piece in the effective action takes the form of a topological three-dimensional photon mass. The topological mass of the photon turns to be imaginary and signals instability. A stable state corresponds to a solution of the Beltrami equations. We demonstrate also that the interaction between two current loops reduces to the linking number of the loops. As for the chiral magnetic effect it seems to disappear in the far infrared.

hep-th↗

arXiv2012

Chiral Vortical Effect in Fermi Liquid

In this note we consider non-relativistic rotating fermi liquid in the presence of Berry curvature. The behavior of the system is then almost the same as in external magnetic field. We argue that there appears an analogue of chiral vortical effect in the liquid if Berry curvature has a non-vanishing flux through sheets of Fermi surfaces and chemical potentials are different. We also claim that quantum anomalies in condensed matter context provide a theoretical and experimental testing ground for the origin of chiral effects, their carriers etc.

cond-mat.mes-hall↗