Search results for "electrodynamics"

Energy oscillations and a possible route to chaos in a modified Riga dynamo

2010

Starting from the present version of the Riga dynamo experiment with its rotating magnetic eigenfield dominated by a single frequency we ask for those modifications of this set-up that would allow for a non-trivial magnetic field behaviour in the saturation regime. Assuming an increased ratio of azimuthal to axial flow velocity, we obtain energy oscillations with a frequency below the eigenfrequency of the magnetic field. These new oscillations are identified as magneto-inertial waves that result from a slight imbalance of Lorentz and inertial forces. Increasing the azimuthal velocity further, or increasing the total magnetic Reynolds number, we find transitions to a chaotic behaviour of th…

Neutral-current effects in elastic electron-nucleon scattering

1974

Parity-violating asymmetry in elastic electron-nucleus scattering due to weak neutral currents

1980

Parity-violating asymmetries are calculated for elastic scattering of electrons on nuclei of arbitrary spin and isospin. Possible dependences on nuclear-model input are shown to be weak. Elastic electron scattering at intermediate energies may become an important tool in studying the structure of hadronic weak neutral currents.

Erratum to: A semi-classical derivation of the spin-orbit electromagnetic interaction

1973

Magnus expansion and the two-neutrino oscillations in matter

1990

We show that the Magnus expansion can help to deal with the problem of matter-neutrino oscillations in the nonadiabatic regime of the two-neutrino-flavor case. An analytic result for the electron-neutrino survival probability is derived in a quite simple way without reference to any particular electron density.

Lattice quantum hadrodynamics

1992

Quantum corrections to the mean-field equation of state for nuclear matter are estimated in a lattice simulation of quantum hadrodynamics. In contrast with the standard coordinate-space methods used in lattice QCD, the calculations are carried out here in momentum space and on nonhypercubic (irregular) lattices. The quantum corrections to the known mean-field equation of state were found to be considerable.

LOCAL STRONG AND COULOMB POTENTIALS IN THE THREE-NUCLEON SYSTEM

1976

Publisher Summary This chapter focuses on local strong and Coulomb potentials in the three-nucleon system. Attempts to use local potentials in three-nucleon calculations with the Faddeev equations are impeded by the fact that for increasing energies contributions from higher and higher subsystem, angular momentum states become important, which quickly make the system of coupled equations unwieldy. However, if long-range interactions such as the Coulomb potential were added, such a procedure would not be useful at all. Several approaches exist that deal with the problems arising from the infinite range of the latter. In the work of Noble and Bencze, the Faddeev equations are modified so that…

Position space formulation for Dirac fermions on honeycomb lattice

2014

We study how to construct Dirac fermion defined on the honeycomb lattice in position space. Starting from the nearest neighbor interaction in tight binding model, we show that the Hamiltonian is constructed by kinetic term and second derivative term of three flavor Dirac fermions in which one flavor has a mass of cutoff order and the other flavors are massless. In this formulation the structure of the Dirac point is simplified so that its uniqueness can be easily shown even if we consider the next-nearest neighbor interaction. We also show the chiral symmetry at finite lattice spacing, which protects the masslessness of the Dirac fermion, and discuss the analogy with the staggered fermion f…

Casimir-Polder interaction between an accelerated two-level system and an infinite plate

2007

We investigate the Casimir-Polder interaction energy between a uniformly accelerated two-level system and an infinite plate with Dirichlet boundary conditions. Our model is a two-level atom interacting with a massless scalar field, with a uniform acceleration in a direction parallel to the plate. We consider the contributions of vacuum fluctuations and of the radiation reaction field to the atom-wall Casimir-Polder interaction, and we discuss their dependence on the acceleration of the atom. We show that, as a consequence of the noninertial motion of the two-level atom, a thermal term is present in the vacuum fluctuation contribution to the Casimir-Polder interaction. Finally we discuss the…

Optimization of population transfer by adiabatic passage

2002

We examine the adiabatic limit of population transfer in two-level models driven by a chirped laser field. We show that the nonadiabatic correction is minimized when the adiabatic eigenenergies associated to the dynamics are parallel. In the diagram of the difference of the eigenenergy surfaces as a function of the parameters, this corresponds to an adiabatic passage along a level line. The analytical arguments are based on the Dykhne-Davis-Pechukas treatment. We illustrate this behavior with various examples.