arXiv subjects

A. V. Prozorkevich

Publications and source records attributed to A. V. Prozorkevich.

At least 19 recordsLinked to original sources

arXiv2014

WKB - type approximations in the theory of vacuum particle creation in strong fields

Within the theory of vacuum creation of an $e^{+}e^{-}$ - plasma in the strong electric fields acting in the focal spot of counter-propagating laser beams we compare predictions on the basis of different WKB-type approximations with results obtained in the framework of a strict kinetic approach. Such a comparison demonstrates a considerable divergence results. We analyse some reasoning for this observation and conclude that WKB-type approximations have an insufficient foundation for QED in strong nonstationary fields. The results obtained in this work on the basis of the kinetic approach are most optimistic for the observation of an $e^{+}e^{-}$ - plasma in the range of optical and x-ray laser facilities. We discuss also the influence of unphysical features of non-adiabatic field models on the reliability of predictions of the kinetic theory.

physics.plasm-ph↗

arXiv2013

Properties of the electron-positron plasma created from vacuum in a strong laser field. Quasiparticle excitations

Solutions of a kinetic equation are investigated which describe, on a nonperturbative basis, the vacuum creation of quasiparticle electron-positron pairs due to a strong laser field. The dependence of the quasiparticle electron (positron) distribution function and the particle number density is explored in a wide range of the laser radiation parameters, i.e., the wavelength λand amplitude of electric field strength E_0. Three domains are found: the domain of vacuum polarization effects where the density of the e-e+ pairs is small (the "calm valley"), and two accumulation domains in which the production rate of the e-e+ pairs is strongly increased and the e-e+ pair density can reach a significant value (the short wave length domain and the strong field one). In particular, the obtained results point to a complicated short-distance electromagnetic structure of the physical vacuum in the domain of short wavelengths λ\lessim λ_{acc} = π/m. For moderately strong fields E_0 \lesssim E_c=m^2/e, the accumulation regime can be realized where a plasma with a high density of e-e+ quasiparticles can be achieved. In this domain of the field strengths and in the whole investigated range of wavelengths, an observation of the dynamical Schwinger effect can be facilitated.

physics.plasm-ph↗

arXiv2012

Photon cluster excitation mechanism in an e-e+ plasma created from vacuum by a strong electromagnetic field

In the low density approximation of nonperturbative kinetic theory we investigate the vacuum creation of an electron-positron plasma (EPP) under the action of an external monochromatic "laser" electric field with the focus on multiphoton processes. We analyse in some detail the role of the photon cluster mechanism of EPP excitation and show that this mechanism plays the dominating role in the case when a large photon number from the external field reservoir takes part in the breakdown of the energy gap. We obtain the distribution function in this approximation and discuss its properties.

physics.plasm-ph↗

arXiv2012

Influence of Laser Pulse Parameters on the Properties of e-e+ Plasmas Created from Vacuum

We use the low density approximation within the kinetic theory approach to vacuum creation of an e-e+ pair plasma (EPPP) in a strong laser field in order to investigate the dependence of the observed EPPP on the form and parameters of a single laser pulse. The EPPP distribution function is calculated for an arbitrary time dependence of the electric field in the multiphoton domain (adiabaticity parameter gamma >> 1). The dependence on the field strength, the form and spectrum of the field pulse is investigated on the basis both analytical and numerical methods. The obtained results can be useful for examining some observable secondary processes associated with the dynamical Schwinger effect.

physics.plasm-ph↗

arXiv2010

A proposal for testing subcritical vacuum pair production with high power lasers

We present a proposal for testing the prediction of non-equilibrium quantum field theory below the Schwinger limit. The proposed experiments should be able to detect a measurable number of gamma rays resulting from the annihilation of pairs in the focal spot of two opposing high intensity laser beams. We discuss the dependence of the expected number of gamma rays with the laser parameters and compare with the estimated background level of gamma hits for realistic laser conditions.

hep-ph↗

arXiv2008

Dynamical Schwinger effect and high-intensity lasers. Realising nonperturbative QED

We consider the possibility of experimental verification of vacuum e^+e^- pair creation at the focus of two counter-propagating optical laser beams with intensities 10^{20}-10^{22} W/cm^2, achievable with present-day petawatt lasers, and approaching the Schwinger limit: 10^{29} W/cm^2 to be reached at ELI. Our approach is based on the collisionless kinetic equation for the evolution of the e^+ and e^- distribution functions governed by a non-Markovian source term for pair production. As possible experimental signals of vacuum pair production we consider e^+e^- annihilation into gamma-pairs and the refraction of a high-frequency probe laser beam by the produced e^+e^- plasma. We discuss the dependence of the dynamical pair production process on laser wavelength, with special emphasis on applications in the X-ray domain (X-FEL), as well as the prospects for μ^+μ^- and π^+π^- pair creation at high-intensity lasers. We investigate perspectives for using high-intensity lasers as ``boosters'' of ion beams in the few-GeV per nucleon range, which is relevant, e.g., to the exploration of the QCD phase transition in laboratory experiments.

physics.plasm-ph↗

arXiv2007

Inertial mechanism: dynamical mass as a source of particle creation

A kinetic theory of vacuum particle creation under the action of an inertial mechanism is constructed within a nonpertrubative dynamical approach. At the semi-phenomenological level, the inertial mechanism corresponds to quantum field theory with a time-dependent mass. At the microscopic level, such a dependence may be caused by different reasons: The non-stationary Higgs mechanism, the influence of a mean field or condensate, the presence of the conformal multiplier in the scalar-tensor gravitation theory etc. In what follows, a kinetic theory in the collisionless approximation is developed for scalar, spinor and massive vector fields in the framework of the oscillator representation, which is an effective tool for transition to the quasiparticle description and for derivation of non-Markovian kinetic equations. Properties of these equations and relevant observables (particle number and energy densities, pressure) are studied. The developed theory is applied here to describe the vacuum matter creation in conformal cosmological models and discuss the problem of the observed number density of photons in the cosmic microwave background radiation. As other example, the self-consistent evolution of scalar fields with non-monotonic self-interaction potentials (the W-potential and Witten - Di Vecchia - Veneziano model) is considered. In particular, conditions for appearance of tachyonic modes and a problem of the relevant definition of a vacuum state are considered.

hep-ph↗

arXiv2007

Laser acceleration of ion beams

We consider methods of charged particle acceleration by means of high-intensity lasers. As an application we discuss a laser booster for heavy ion beams provided, e.g. by the Dubna nuclotron. Simple estimates show that a cascade of crossed laser beams would be necessary to provide additional acceleration to gold ions of the order of GeV/nucleon.

physics.acc-ph↗

arXiv2005

Pair production and optical lasers

Electron-positron pair creation in a standing wave is explored using a parameter-free quantum kinetic equation. Field strengths and frequencies corresponding to modern optical lasers induce a material polarisation of the QED vacuum, which may be characterised as a plasma of e^+ e^- quasiparticle pairs with a density of ~10^{20}cm^{-3}. The plasma vanishes almost completely when the laser field is zero, leaving a very small residual pair density, n_r, which is the true manifestation of vacuum decay. The average pair density per period is proportional to the laser intensity but independent of the frequency, ν. The density of residual pairs also grows with laser intensity but n_r \propto ν^2. With optical lasers at the forefront of the current generation, these dynamical QED vacuum effects may generate 5-10 observable two-photon annihilation events per laser pulse.

nucl-th↗

arXiv2004

Vacuum creation of massive vector bosons and its application to a conformal cosmological model

In the simple model of a massive vector field in flat space-time, we derive a kinetic equation of non-Markovian type, describing the vacuum pair creation under the action of external fields of different nature. We use for this aim the non-perturbative methods of kinetic theory in combination with a new element when the transition of the instantaneous quasiparticle representation is realized within the oscillator (holomorphic) representation. We study in detail the process of vacuum creation of vector bosons generated by a time-dependent boson mass in accordance with a conformal-invariant scalar-tensor gravitational theory and its cosmological application. It is indicated that the choice of the equation of state (EoS) of the Universe allows to obtain a number density of the vector bosons that is sufficient to explain the observed number density of photons in the cosmic microwave background radiation. It is shown that the vector boson gas created from the vacuum is in a strong non-equilibrium state and corresponds to a cold dust-like EoS.

hep-ph↗

arXiv2004

Pulsations of the electron-positron plasma in the field of optical lasers

The possibility to observe vacuum electron-positron pair creation due to a powerful optical laser pulse is discussed. We employ a quantum kinetic formulation of the problem with a source term describing the vacuum pair production in a homogeneous electric field with arbitrary time dependence (dynamical Schwinger mechanism). For a periodic field weak in comparison with the critical value E_{cr}=m^2/|e|, the electron-positron plasma density changes approximately periodically with twice the field frequency. Under these conditions, the mean value $ $ for the density per period in the volume lambda^3 is a more appropriate characteristic quantity than the residual density n_r which is taken over an integer number of field periods and calculated using the imaginary time method. The value is proportional to the squared field intensity and does not depend on the frequency. We show that in terms of the parameter an optical laser can be more effective than a X-ray one. We expect that it is possible to observe the vacuum creation effect not only by means of the planned X-ray free electron lasers but already at present-day optical lasers.

physics.plasm-ph↗

arXiv2004

Vacuum creation of quarks at the time scale of QGP thermalization and strangeness enhancement in heavy-ion collisions

The vacuum parton creation in quickly varying external fields is studied at the time scale of order 1 fm/$c$ typical for the quark-gluon plasma formation and thermalization. To describe the pre-equilibrium evolution of the system the transport kinetic equation is employed. It is shown that the dynamics of production process at times comparable with particle inverse masses can deviate considerably from that based on classical Schwinger-like estimates for homogeneous and constant fields. One of the effects caused by non-stationary chromoelectric fields is the enhancement of the yield of $s\bar{s}$ quark pairs. Dependence of this effect on the shape and duration of the field pulse is studied together with the influence of string fusion and reduction of quark masses.

nucl-th↗

arXiv2004

The kinetic equation for the quark Wigner function in strong gluon field

The Vlasov type quantum kinetic equation for deconfined quarks in strong quasi-classical gluon field is derived in the covariant single-time formalism. The equations system for the Wigner function components is obtained as a result of spinor and color decomposition. The field-free and vacuum solutions of the kinetic equation are found, and the conservation laws are derived. The flux-tube configuration of gluon field is discussed in detail.

hep-ph↗

arXiv2003

Kinetic Theory of the Quantum Field Systems With Unstable Vacuum

The description of quantum field systems with meta-stable vacuum is motivated by studies of many physical problems (the decay of disoriented chiral condensate, the resonant decay of CP-odd meta-stable states, self-consistent model of QGP pre-equilibrium evolution, the phase transition problem in the systems with broken symmetry etc). A non-perturbative approach based on the kinetic description within the framework of the quasi-particle representation was proposed here. We restrict ourselves to scalar field theory with potentials of polynomial type. The back reaction mechanism, i.e. the particle production influence on background field is also discussed. Using the oscillator representation, we derive the generalized kinetic equation with non-pertrubative source term for description of particle-antiparticle creation under action of background field and equation of motion for it. As an illustrative example we consider one-component scalar theory with double-well potential. On this example, we study some features of proposed approach, in particular, the selection problem of stable vacuum state, what allows to avoid appearance of tachyonic regimes. The similar analysis is possible for some other models of such kind: the Friedberg-Lee model, the non-linear of $η$ -- meson model of Witten--Di Vecchia--Veneziano, end so on.

hep-th↗

arXiv2003

The kinetic description of vacuum particle creation in the oscillator representation

The oscillator representation is used for the non-perturbative description of vacuum particle creation in a strong time-dependent electric field in the framework of scalar QED. It is shown that the method can be more effective for the derivation of the quantum kinetic equation (KE) in comparison with the Bogoliubov method of time-dependent canonical transformations. This KE is used for the investigation of vacuum creation in periodical linear and circular polarized electric fields and also in the case of the presence of a constant magnetic field, including the back reaction problem. In particular, these examples are applied for a model illustration of some features of vacuum creation of electron-positron plasma within the planned experiments on the X-ray free electron lasers.

hep-th↗

arXiv2001

Plasma production and thermalisation in a strong field

Aspects of the formation and equilibration of a quark-gluon plasma are explored using a quantum kinetic equation, which involves a non-Markovian, Abelian source term for quark and antiquark production and, for the collision term, a relaxation time approximation that defines a time-dependent quasi-equilibrium temperature and collective velocity. The strong Abelian field is determined via the simultaneous solution of Maxwell's equation. A particular feature of this approach is the appearance of plasma oscillations in all thermodynamic observables. Their presence can lead to a sharp increase in the time-integrated dilepton yield.

nucl-th↗

arXiv2000

Pair creation and plasma oscillations

We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background field and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses.

nucl-th↗

arXiv2000

A Covariant Generalization of the Real-Time Green's Functions Method in the Theory of Kinetic Equations

A generalized quantum kinetic equation (RKE) of the Kadanoff-Baym type is obtained on the basis of the Heisenberg equations of motion where the time evolution and space translation are separated from each other by means of the covariant method. The same approach is used also for a covariant modification of the real-time Green's functions method based on the Wigner representation. The suggested approach does not contain arbitrariness' elements and uncertainties which often arise from derivation of RKE on the basis of the motion equations of the Kadanoff-Baym type for the correlation functions in the case of systems with inner degrees of freedom. Possibilities of the proposed method are demonstrated by examples of derivation of RKE of the Vlasov type and collision integrals of the Boltzmann-Uehling-Uhlenbeck (BUU) type in the frame of the $σω$ -version of quantum hadrodynamics, for the simplest case of spin saturated nuclear matter without antinuclear component. Here, the quasiparticle approximation in a covariant performance is used. A generalization of the method for the description of strong non-equilibrium states based on the non-equilibrium statistical operator is then proposed as well.

hep-ph↗