Pair creation in the field of a moving charge

We consider the creation of fermion and boson pairs in the field of a charge moving in a circle. We show that the effect is observable for χ=(Ω/m)(E/m_Q)²～ 1.     

Pair production in an electric field applied for a short time

An expression is obtained for the probability of pair production in a homogeneous electric field applied for a short time and a constant inhomogeneous magnetic field when both fields have the same direction. The dependence of the probability is investigated for short and long times of application of the electric field.     

Pair creation by a non-local potential

The probability of pair creation by a separable and non-local potential is considered following the Schwinger approach. It has been found that this probability is null. As a particular case, the separable δ-potential is considered and the probability is also found null.     

Particle creation in a time-dependent electric field revisited

We adopt the general formalism for analyzing evolution of gaussian states of quantized fields in time-dependent backgrounds in the Schrodinger picture (presented in detail in Mahajan and Padmanabhan [G. Mahajan, T. Padmanabhan, Gen. Rel. Grav. 40 (2008) 661]) to study the example of a spatially uniform electric field background (in a time-dependent gauge) which is kept turned on for a finite duration of time. In particular, we study the time-dependent particle content, defined in terms of the concept of instantaneous eigenstates, and describe how it captures the time evolution of the quantized field modes. The actual particle creation process occurs over a relatively short interval in time, and the particle content saturates rather quickly. We also compare the power spectrum of the field modes, computed in the asymptotic limit, with the corresponding situation in a cosmological de Sitter background. Particle creation under the influence of a spiked electric field localized in time, as a particular limiting case of the above general model, is also considered.     

Pair creation by internal conversion

In this report we describe the general theory of internal electron-positron pair conversion. Within the point nucleus approximation we derive analytical formulae for the differential pair conversion coefficient using Coulomb wave functions for the electron. Numerical calculations of the pair conversion coefficient for pointlike and extended nuclei for various multipolarities, transition energies and nuclear charges are presented and compared with Born approximation results and experimental data.     

Erratum to: Peculiarities of pair creation by a peak electric field

Russian Physics Journal -     

Magnetic field creation by electron-weak interaction in a gravitational field

We give rough arguments showing that a stationary gravitational field should produce a magnetic field by vacuum polarization effects on neutrinos and electrons.     

Entanglement of a mesoscopic field with an atom induced by photon graininess in a cavity

We observe that a mesoscopic field made of several tens of microwave photons exhibits quantum features when interacting with a single Rydberg atom in a high-Q cavity. The field is split into two components whose phases differ by an angle inversely proportional to the square root of the average photon number. The field and the atomic dipole are phase entangled. These manifestations of photon graininess vanish at the classical limit. This experiment opens the way to studies of large quantum state superpositions at the quantum-classical boundary.     

Incommensurate phases induced by an electric field

All magnetic symmetry classes for which the two-dimensional representations are physically irreducible are enumerated. These representations admit of the Lifshitz invariant induced by an external electric field aligned parallel to the principal axis of the crystal. In the majority of the cases, this field does not split two-dimensional representations into one-dimensional representations and, therefore, an incommensurate phase arises in an arbitrarily weak field. The representations of the magnetic classes C _4h and C′_4h are considered in close detail. The components of the toroidal momentum are chosen as the components of the order parameter.     

Dimensional crossover driven by an electric field

We study the steady-state dynamics of the Hubbard model driven out of equilibrium by a constant electric field and coupled to a dissipative heat bath. For a very strong field, we find a dimensional reduction: the system behaves as an equilibrium Hubbard model in lower dimensions. We derive steady-state equations for the dynamical mean-field theory in the presence of dissipation. We discuss how the electric field induced dimensional crossover affects the momentum resolved and integrated spectral functions, the energy distribution function, as well as the steady current in the nonlinear regime.     

Formation of a pair and an electron by a photon in the field of a nucleus

A general expression is calculated for the differential cross section of the formation of an electron-positron pair and a photon by a photon in the Coulomb field of an atomic nucleus. Particular kinematic cases of the process which have not previously been investigated are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 91–96, October, 1978.