Relativistic generalization of the Keldysh ionization theory

A relativistic theory of tunneling is developed. Ionization of atoms and ions by a constant crossed field and an ultrashort laser pulse, ionization probability as a function of the adiabaticity parameter and the pulse shape, the limit of the Keldysh nonrelativistic ionization theory, and the photoelectron momentum spectrum are considered. In calculations, the imaginary time method is used.     

Strong field ionization by ultrashort laser pulses: Application of the Keldysh theory

Analytical expressions and numerical results describing ionization of atoms by intense linearly polarized ultrashort laser pulses are obtained in the frame of the Keldysh approach. Photoelectron spectra and total ionization probabilities are presented for several analytical models of a single-cycle laser pulse. In particular, strong left-right asymmetry of the spectra is shown for the case of odd pulses.     

On the relativistic theory of tunneling

A relativistic generalization of the semiclassical theory of tunneling and multiphoton ionization of atoms and ions in the field of a high-intensity electromagnetic wave with linear, circular, and elliptic polarization is constructed. The exponential factor in the ionization probability is calculated for arbitrary values of adiabaticity parameter γ. In the case of low-frequency laser radiation, an asymptotically exact formula is derived for the ionization rate of the s atomic level, including the Coulomb, spin, and adiabatic corrections and the preexponential factor.     

On a generalization of the Einstein-Cartan theory and the Klein-Kaluza theory

The Klein-Kaluza theory with a nonvanishing torsion is developed. The torsion is associated with the spin and polarization of an electromagnetic field. The electromagnetic polarization is considered as a source of additional components of a torsion connected with a fifth dimension. It is proved that the new effects are 10³⁶ times bigger than the effects from the Einstein-Cartan theory. Partially supported by Polish Ministry of Science, Higher Education and Technology, project No. Mr 17.     

On the formalism of relativistic many body theory

The thermodynamic potential is constructed as an effective action functional of the various n point amplitudes (n ? 4). One of the functionals is used to obtain the equations of state as simple, convergent expressions involving the conventionally renormalized charges and masses.     

A new approach to the theory of Cherenkov radiation based on relativistic generalization of the Landau criterion

Relativistic generalization of the Landau criterion is obtained which, in contrast to the classical Tamm-Frank and Ginzburg theories, determines the primary energy mechanism of emission of nonbremsstrahlung Cherenkov radiation. It is shown that Cherenkov radiation may correspond to a threshold energetically favorable conversion of the condensate (ultimately long-wavelength) elementary Bose perturbations of a medium into transverse Cherenkov photons emitted by the medium proper during its interaction with a sufficiently fast charged particle. The threshold conditions of emission are determined for a medium with an arbitrary refractive index n, including the case of isotropic plasma with n<1 for which the classical theory of Cherenkov radiation prohibits such direct and effective nonbremsstrahlung emission of these particular transverse high-frequency electromagnetic waves. It is established that these conditions of emission agree with the data of well-known experiments on the threshold for observation of Cherenkov radiation, whereas the classical theory only corresponds to the conditions of observation of the interference maximum of this radiation. The possibility of direct effective emission of nonbremsstrahlung Cherenkov radiation, not taken into account in the classical theory, is considered for many observed astrophysical phenomena (type III solar radio bursts, particle acceleration by radiation, etc.).     

On the relativistic field theory model of the deuteron II

The relativistic field theory model of the deuteron suggested previously is revised and applied to the calculation of the cross sections of the low-energ radiative neutron-proton capture n + p → D + γ and the low-energy two-proton fusion p + p → D + e⁺ + ν_e. For the low-energy data and the potential model prediction. In the case of the two-proton fusion the cross section obtained is 2.9 times as much as that given by the potential approach. The obtained result is discussed in connection with the solar neutrino problem.     

On relativistic kinetic gas theory: XV. The Ritz method in relativistic Boltzmann theory

The transport coefficients of a multicomponent gas mixture are approximated by means of a variational technique. It is shown that the procedure is equivalent to a more heuristic method developed earlier.     

On the degree of ionization in the TFW theory

We give a simplified proof of the theorem which says that in Thomas-Fermi-Von Weizsaecker theory the surplus charge of bounded electrons cannot exceed the combined charge of the nuclei in absolute value.     

On the Thomas precession in the classical theory of relativistic radiation

It is demonstrated that the radiation of the angular momentum power of electromagnetic field is directly proportional to the Thomas precession frequency. Thereby the dynamical aspect of origin of this phenomenon is established for the first time.     

On the theory of atomic ionization following alpha decay

The -decay of a nucleus may cause atomic ionization. One of the basic assumptions of Migdal's original paper, which is the prototype of all later calculations for this process, is to treat the -particle outside the nuclear region classically as a point charge moving along a definite trajectory. In contrast to this picture, in the standard quantum-mechanical model of the -decay, the -particle is represented by a wave function that, after tunneling through the Coulomb barrier at the nuclear surface, propagates outwards as a spherical wave. We compare these two pictures within a three-body model, clarify the conditions under which the full quantum-mechanical calculation and its semiclassical counterpart give similar results and also point out the origin of their possible discrepancies.This paper is dedicated to the memory of A. B. Migdal. His bright physical intuition, which guided him in his pioneering work on this subject—as in many cases later on-, proved to be essentially correct     

A generalization of the classical moment problem on *-algebras with applications to relativistic quantum theory. II

We discuss some properties of a non-commutative generalization of the classical moment problem (them-problem) previously introduced. It is shown that there is a connexion between the determination of the problem and the self-adjointness properties in the corresponding Hilbert space. This generalizes the well-known connexion between the determination of the measure in the classical moment problem and the self-adjointness properties of the polynomials as operators in the correspondingL ²-space. The dependence of them-problem on the choice ofC*-semi-norms and on the action of *-homomorphisms is also investigated. As an application, it is shown that if a quantum field (in a very general sense) is essentially self-adjoint then them-problem for the Wightman functional is determined on the quasi-localizableC*-algebra and that the corresponding representation of the localizable algebra generates the bounded observables of the field. It is pointed out that (ultraviolet and spatially) cut-off fields fall in this class and, therefore, are in one to one correspondance with states on the quasi-localizableC*-algebra.Laboratoire associé au Centre National de la Recherche Scientifique.     

On the relativistic invariance of a quantum theory based on beables

We discuss the question of the relativistic invariance of a quantum theory based on beables, and we suggest the general outlines of one possible form of such a theory.     

On the geometric structure of a parity-conserving relativistic quantum field theory

Wheeler's conjecture that there might exist a ‘principle’ which rules out parity-non-conserving spaces is analysed. The following result has been obtained: A local relativistic quantum field theory is parity-conserving if the following conditions hold:

1. The fields are derived from geometry, i.e. they are represented by quantised currents (in the sense of de Rham); and
2. The theory may be defined on a connected and, under certain restrictions, on a disconnected orientable space-time continuumM ⁴.

     

On the keldysh ionization theory for ultrashort laser pulses

A closed analytical expression is obtained for the momentum distribution of photoelectrons from the ionization of atoms or ions by an ultrashort laser pulse. This formula is applied to analyze some models of electromagnetic pulses and the interference effect in the ionization probability.