We speculate that above or just below the electroweak phase transition magnetic fields are generated which have a net helicity (otherwise said, a ChernSimons term) of order of magnitude NB + NL, where NB,L is the baryon or lepton number today. (To be more precise requires much more knowledge of B,L-generating mechanisms than we currently have.) Electromagnetic helicity generation is associated ...

Three-dimensional (3D) turbulence has both energy and helicity as inviscid constants of motion. In contrast to two-dimensional (2D) turbulence, where a second inviscid invariant— the enstrophy—blocks the energy cascade to small scales, in 3D there is a joint cascade of both energy and helicity simultaneously to small scales. It has long been recognized that the crucial difference between 2D and...

Two spectral regimes of magnetic field amplification in magnetohydrodynamic (MHD) flows can be distinguished by the scale on which fields are amplified relative to the primary forcing scale of the turbulence. For field amplification at or below the forcing scale, the amplification can be called a “small scale dynamo.” For amplification at and above the forcing scale the process can be called a ...

The ’dyon’ system of D’Hoker and Vinet consisting of a spin 1 2 particle with anomalous gyromagnetic ratio 4 in the combined field of a Dirac monopole plus a Coulomb plus a suitable 1/r potential (which arises in the long-range limit of a self-dual monopole) is studied following Biedenharn’s approach to the Dirac-Coulomb problem: the explicit solution is obtained using the ‘Biedenharn-Temple op...

The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery , more than 70 years ago , that the proton is not elementary , the observation of Bjorken scaling in the late 1960s lead to the idea of hadrons containing almost pointlike...

X-ray beams with orbital angular momentum (OAM) are a promising tool for x-ray characterization techniques. Beams OAM have helicity--an azimuthally varying phase--which leads to gradient of the light field. New material properties can be probed by utilizing helicity an beam. Here, we demonstrate novel dichroic effect in resonant diffraction from artificial antiferromagnet topological defect. We...

We present a new technique for the calculation of helicity ±1/2 gravitino production during preheating. It is based on the equivalence between goldstinos and helicity ±1/2 gravitinos at high energies. The problem is thus reduced to the standard (Majorana) fermion production after inflation. Comparison with the results obtained in the unitary gauge is also presented.

Magnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, especially the constraints imposed by magnetic helicity conservation. We estimate the minimal strength of the large-scale magnetic field which could arise inspite of the ...

The conservation of helicity in ideal barotropic fluids is discussed from a group theoretical point of view. A new symmetry group is introduced i.e. the alpha group of translations. It is proven via the Noether theorem that this group generates helicity conservation.