Search results for "Quantum electrodynamics."
showing 10 items of 797 documents
Thermalization of the dispersive three-wave interaction
2007
We investigate the role of dispersion effects on the long-term evolution of the nonlinear three-wave interaction. We show that the three waves exhibit, as a general rule, an irreversible evolution towards a thermodynamic equilibrium state in which they propagate with identical velocities. As a result of this thermalization process, the three-wave system is driven away from spatio-temporal resonance, so that the equilibrium state does not satisfy the (phase-matching) resonant conditions of energy and momentum conservation for the averaged frequencies. Moreover, we show that the interplay between temporal dispersion and spatial diffraction leads to the emergence of a peculiar equilibrium stat…
Finite Nc corrections in the Balitsky-Kovchegov equation at next-to-leading order
2021
Publisher Copyright: © owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). We study the finite-Nc corrections to the next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation. This contains correlators of six Wilson lines, which we express in terms of the two-point function using the Gaussian approximation. Numerically, the effects of these finite-Nc corrections on the NLO BK equation are found to be smaller than the expected 1/Nc2 ∼ 10%. Corrections may be large for individual correlators, but have less of an influence on the shape of the amplitude as a function of the dipole size. There is a…
Residual fluctuations in the microwave background at large angular scales: Revision of the Sachs-Wolfe effect
1993
In this paper we revise the Sachs-Wolfe (SW) computation of large-scale an isotropies of the microwave background temperature, taking into account the properties of the metrics admitting an isotropic distribution of collisionless photons. We show that the metric used by SW belongs to the aforementioned class, and conclude that the microwave background (once the dipolar anisotropy has been subtracted) should now be isotropic at large angular scales, provided that it was isotropic on the last scattering surface and assuming that the growing mode of a pressureless Einstein-de Sitter perturbation is a good description of the metric.
Finite perturbation calculation for the static dipole polarizabilities of the atoms Na through Ca
1976
Effect of external magnetic field on angular momenta distribution
1995
Neutral currents in semi-leptonic processes ΔT=0
1974
It is often argued that between nonstrange (and noncharmed) hadrons the matrix element of the last part of the current can be neglected, and calculations along this line have been performed. If this assumption turns out to be true, the only isoscalar neutral current between nonstrange hadrons is that contained in the electromagnetic one. The consequences are examined.
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.