Search results for "quantum electrodynamics"

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.

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.