Dressed-quark anomalous magnetic moments

Perturbation theory predicts that a massless fermion cannot possess a measurable magnetic moment. We explain, however, that the nonperturbative phenomenon of dynamical chiral symmetry breaking generates a momentum-dependent anomalous chromomagnetic moment for dressed light quarks, which is large at infrared momenta, and demonstrate that consequently these same quarks also possess an anomalous electromagnetic moment with similar magnitude and opposite sign.     

Motion of electron with anomalous moments in parallel electric and magnetic fields

An accurate solution is obtained for the Dirac equation describing the motion of an electron with anomalous moments in constant, homogeneous, and parallel electric and magnetic fields. The system of solutions obtained is shown to be orthogonal and complete with respect to the scalar product defined in the null plane X^oX³=const. The solutions obtained pass smoothly in the limit to steadystate solutions describing the motion of an electron with anomalous moments in a homogeneous magnetic field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 23–28, January, 1978.It remains to thank V. G. Bagrov for useful discussions of the work.     

Motion of neutral fermions with anomalous magnetic and electric moments in external fields

A covariant spin operator is found for fermions with anomalous magnetic and electric dipole moments in constant external fields. The spin behavior of a neutral fermion in constant magnetic and electric fields is investigated using exact solutions obtained for the Dirac equation.     

Quantum gravity and the electron and muon anomalous magnetic moments

Quantum gravity corrections at the one-loop level to the electron and muon $\text{(}\text{g}\text{?2)}\text{2}$ are calculated and found to be finite.     

Passage of relativistic magnetic dipole moments through magnetic fields

We have solved the Dirac equation with an anomalous moment Pauli-coupling exactly for a constant magnetic field and derived the general relativistic formulas for phase changes due to translational motion and spin rotations. We also give transmission and reflection coefficients, spin rotation for tunnelling and barrier penetration. For ultrarelativistic particles the spin rotation angle on the path of lengthL is equal to (2μB L/ħc)[1 +m ² c ⁴/(E²-μ ² B ²)].

     

Particle with anomalous moments in an axial magnetic field

The exact solutions of the generalized phenomenological Dirac equation in an axisymmetrical time-invariant magnetic field are discussed. The influence of an anomalous magnetic and a postulated electric moment on the spectrum of fermions moving in that field is investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 36–39, May, 1981.The author is grateful to Prof. V. G. Bagrov for interest and useful consultations.     

Pair production and vacuum polarization of vector particles with electric dipole moments and anomalous magnetic moments

The matrix 8-component Dirac-like form of the P-odd equations for boson fields of spin 1 and 0 are obtained and the symmetry group of the equations is derived. We found exact solutions of the field equation for vector particles with arbitrary electric and magnetic moments in external constant and uniform electromagnetic fields. The differential probability of pair production of vector particles with electric dipole moments and anomalous magnetic moments by an external constant and uniform electromagnetic field has been found using exact solutions. We have calculated the imaginary and real parts of the electromagnetic field Lagrangian that takes into account the vacuum polarization of vector particles. Received: 14 April 2001 / Revised version: 13 July 2001 / Published online: 19 September 2001     

Surface structure of quark stars with magnetic fields

We investigate the impact of magnetic fields on the electron distribution of the electrosphere of quark stars. For moderately strong magnetic fields of B ∼ 10¹³ G, quantization effects are generally weak due to the large number density of electrons at surface, but can nevertheless affect the photon emission properties of quark stars. We outline the main observational characteristics of quark stars as determined by their surface emission, and briefly discuss their formation in explosive events termed as quark-novae, which may be connected to the r-process.     

AC-driven anomalous stochastic diffusion and chaotic transport in magnetic superlattices

We study regular and chaotic motion of the charge carriers in a two-dimensional electron gas subject to a spatially periodic magnetic field and to an AC electric field. We show how the interplay between the time-periodic electric and the spatially-periodic magnetic field leads to dynamical chaos and to fast stochastic diffusion of the electrons. The cases of a one-dimensional magnetic modulation with AC pumping and of a pure two-dimensional magnetic modulation are compared. We find the direct effect of anomalous diffusion and Lévy flights on the conductivity of a sample.     

Heavy fermion contributions to the anomalous magnetic dipole and quadrupole moments of theW-boson

The contribution of a massivet-quark to the anomalous magnetic moment (Δκ) and the quadrupole moment (ΔQ) of theW-boson is calculated. An upper bound of Δκ=1.5×10^?2 and ΔQ=2.5×10^?3 for the standard model is obtained. Additional contributions from extraE ₆ fermions is also discussed.     

Neutron stars and pulsars

Neutron star models require many “exotic" physical ingredients: cold ultra-dense matter, very strong gravitational and magnetic fields, high-energy radiation in X and gamma range, ... For starting, a short historical review of the notions of pulsar and neutron star are given, theoretical and numerical models for these objects are then detailed, before main observations (available and to come), together with the constraints they are putting on the models are reviewed. The pulsar emission mechanism is sketched and the last part of this introduction describes some observations using neutron stars as probes for modern physics.     

Neutron stars, hybrid stars and the equation of state

Gross properties of hybrid stars consisting of a core of strange matter surrounded by ordinary neutron matter are investigated. We discuss star models based on phenomenological equations of state from nuclear reactions including a phase transition between the hadronic phase and the quark-gluon plasma. For certain parameters, such equations of state support the existence of hybrid stars. The identification of such objects could provide detailed information on the properties of strange quark matter.     

Radial oscillations of neutron stars in strong magnetic fields

The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star masses is minimal.     

Temperature contours and ghost surfaces for chaotic magnetic fields

Steady state solutions for anisotropic heat transport in a chaotic magnetic field are determined numerically and compared to a set of "ghost surfaces"-surfaces constructed via an action-gradient flow between the minimax and minimizing periodic orbits. The ghost surfaces are in remarkable agreement with the temperature contours.     

Neutron diffraction study of UAs in high magnetic fields

Magnetization experiments have shown that at low temperature and in an applied magnetic field of ～90 kOe antiferromagnetic (AF) uranium arsenide transforms to a new ferrimagnetic state. The high-field transition produces a state with magnetic components $\text{parallel}$ to the applied field. A small ferromagnetic component (0.4 μ_B) is seen in magnetization experiments but with neutron diffraction we have observed directly the large AF component (～ 1.8 μ_B) which has a $\text{q}$ value of 0.58 ± 0.01 $\text{c}$¹ in contrast to the zero field type IA structure with $\text{q}\text{= (0,0,0.50)}$. This transition is quite different from that occuring in the conventional spin-flop transition.     

Neutron scattering length of terbium structure refinement and magnetic moments of terbium iron garnet

The neutron scattering length of terbium was redetermined from powder data on terbium iron garnet (TbIG) and TbO₂ by the profile analysis technique. The mean value obtained is b (Tb) = 0.735(10) x 10^?12cm. Furthermore the positional and thermal parameters of TbIG have been refined from single crystal X-ray and neutron powder data. The results from both experiments agree well. The X-ray data from a sphere of diameter φ = 282μm were collected by MoKα radiation. The refinement was carried out including an extinction parameter which was also applied to correct for anomalous transmission. The powder data were treated by the profile analysis technique where the structural parameters and the magnetic moments were refined simultaneously. Two slightly different form factor curves were applied for Fe³⁺ in the crystallographic sites. The magnetic moments for the iron ions were found to be μ = 3.69(10)μ_B for the octahedral and 3.65(10)μ_B for the tetrahedral site at room temperature. The moment for terbium is μ = 1.15(09)μ_B and the whole magnetisation for one formula unit is 0.12(0.40)μ_B. The observed moments of Fe³⁺ are considerably reduced as compared to the free ion spin only value which was calculated from a Brillouin function for $\text{S =}\text{5}\text{2}$ to be 4.34μ_Bat 300 K.     

Effects of magnetic fields on equation of state of rotating stars

The evolution of rotating stars with magnetic fields has been studied with focus given to the following aspects: the effects of magnetic fields on equation of state for stellar matter and the thermodynamic quantities; the effects of magnetic energy and pressure on the internal structure of stars. The differences between the structure and evolution of a 15M⊙rotating star with and without magnetic fields are discussed. Our results show that the magnetic fields have an effect on the structure and evolution of the star mainly during the central helium burning phase; and this influences the physical quantities in the stellar envelope where hydrogen and helium are partially ionized. This may influence stellar pulsation.     

Regular and chaotic dynamics of a chain of magnetic dipoles with moments of inertia

The nonlinear dynamic modes of a chain of coupled spherical bodies having dipole magnetic moments that are excited by a homogeneous ac magnetic field are studied using numerical analysis. Bifurcation diagrams are constructed and used to find conditions for the presence of several types of regular, chaotic, and quasi-periodic oscillations. The effect of the coupling of dipoles on the excited dynamics of the system is revealed. The specific features of the Poincaré time sections are considered for the cases of synchronous chaos with antiphase synchronization and asynchronous chaos. The spectrum of Lyapunov exponents is calculated for the dynamic modes of an individual dipole.