Ciprian Dariescu

SU (2)× U (1) Gauge theory of bosonic and fermionic fields inS 3× R space-time

The tetradic Lorentz-gauge invariant formulation of the SU(2) × U(1) theory in S3 × R space-time is presented and the general gauge covariant Dirac-Klein-Gordon-Maxwell-Yang-Mills equations are derived. A direct comparison of these equations to those of the SU(2) × U(1) gauge theory on Minkowskian background points out major differences effectively induced by the minimally coupling to S3 × R gravity.

U(1) gauge theory for charged bosonic fields on R times S sup 3 topology

A model for U(1) gauge theories over a compact Lie group is described usingR×S3 as background space. A comparison with other results is given. Electrodynamics equations are obtained. Finally, some considerations and observations about gravity onR×S3 space are presented.

First-order perturbative approach to charged boson stars

Abstract As it is known by now, the boson stars are gravitationally bound, both globally U (1) and spherically symmetric, compact equilibrium configurations of cold complex scalar fields. The aim of the present Letter is to study the ( SO (3,1)× U (1))-gauged minimally coupled charged spinless field to a spherically symmetric spacetime and to analytically derive the first-order approximating solutions to the system of Klein–Gordon–Maxwell–Einstein equations. The instabilities we study could lead to the formation of boson stars from an initially smooth state. The corresponding (analytical) formulae for the charge, mass and radius of the boson stars can accommodate a wide range of numerical estimations, by tuning the model parameters.

Approximative analytic study of fermions in magnetar’s crust; ultra-relativistic plane waves, Heun and Mathieu solutions and beyond

Working with a magnetic field periodic along Oz and decaying in time, we deal with the Dirac-type equation characterizing the fermions evolving in magnetar’s crust. For ultra-relativistic particles, one can employ the perturbative approach, to compute the conserved current density components. If the magnetic field is frozen and the magnetar is treated as a stationary object, the fermion’s wave function is expressed in terms of the Heun’s Confluent functions. Finally, we are extending some previous investigations on the linearly independent fermionic modes solutions to the Mathieu’s equation and we discuss the energy spectrum and the Mathieu Characteristic Exponent.

Charged Scalars in Transient Stellar Electromagnetic Fields

We consider a non-rotating strongly magnetized object, whose magnetic induction is of the form Bx = B0(t)sin?Z. In the electromagnetic field generated by only one component of the four-vector potential, we solve the Klein?Gordon equation and discuss the sudden growth of the scalar wave functions for wavenumbers inside computable ranges. In the case of unexcited transversal kinetic degrees, we write down the recurrent differential system for the amplitude functions and compute the respective conserved currents.

Persistent currents and critical magnetic field in planar dynamics of charged bosons

The aim of the present paper is the analysis from both quantum mechanics and thermodynamic points of view of the Hall-type behaviour of a relativistic charged scalar particle. Starting with the Euler–Lagrange equation, we obtain the solution and the Landau-type energy levels which exhibit a general dependence on the exterior electric and magnetic fields and on the particle momentum. For an ultra-relativistic particle, the characteristic function allows us to derive the so-called persistent currents, the state equation and the magnetization. In the last section, we add a self-interacting contribution to the Lagrangian and we get the critical magnetic induction values when the symmetry of the model is restored.

Transition rates in charged boson nebulae

Abstract Using the first-order approximating solutions to the Einstein–Maxwell–Klein–Gordon system of equations for a complex scalar field minimally coupled to a spherically symmetric spacetime, we study the feedback of gravity and electric field on the charged scalar source. Within a perturbative approach, we compute, in the radiation zone, the transition amplitudes and the coherent source-field regeneration rate.

Rotationally Symmetric Massless Modes in Closed Robertson-Walker Universe

The aim of the present paper is to investigate the minimally coupled rotationally symmetric scalar field configurations in spatially closed Friedman-Robertson-Walker Universe with incoherent dust. We have got the closed form solution of the Klein-Gordon equation in terms of two real-valued linearly independent hypergeometric functions. The orthonormal set of positive-frequency-like parity modes thereafter derived points out that each parity given state is conformally built up of three Einsteinian particle states and also leads to the explicit coordinate-representation of the field propagator.

Charged black holes on the Taub-Bolt instanton

We construct a new exact solution of the Einstein-Maxwell-Dilaton field equations in five dimensions, which describes a system of two general charged and static black holes sitting at the two turning points of the Taub-bolt instanton. We show that in this case the conical singularities can be completely eliminated and the black hole system remains in static equilibrium. We show how to recover some of the known solutions in particular cases and also obtain as a new solution the extremal double-black hole solution on the Taub-bolt instanton. Finally, we compute the conserved charges and investigate some of the thermodynamic properties of this system.

A Maxwell Field Equations Class of Exact Solutions on Matter-Dominated Spatially Closed Friedman-Robertson-Walker Universe

Working in a spatially closed Friedman-Robertson-Walker universe with cosmological dust, we investigate a particular source-free Maxwell field generated by a rotationally-symmetric potential A with one of the components in the direction of θ and the other along β. Using the (α, β, θ)-Euler coordinates on S3 and a compact timelike coordinate f, we obtain a class of parametric solutions that allows us to write down the essential components of the Maxwell tensor as well as the induction and the electric field intensity pointing out, besides the non-propagating fundamental electric field, a “burst” of electromagnetic radiation.