412 research outputs found
On chirality of the vorticity of the Universe
We study chirality of the vorticity of the Universe within the
Einstein-Cartan cosmology. The role of the spin of fermion species during the
evolution of the Universe is studied by averaged spin densities and
Einstein-Cartan equations. It is shown that spin density of the light Majorana
neutrinos acts as a seed for vorticity at early stages of the evolution of the
Universe. Its chirality can be evaluated in the vicinity of the spacelike
infinity. It turns out that vorticity of the Universe has right-handed
chirality.Comment: 7 pages; new estimates, clarifications and references added;
published versio
Chiral Shock Waves
We study the shock waves in relativistic chiral matter. We argue that the
conventional Rankine-Hugoinot relations are modified due to the presence of
chiral transport phenomena. We show that the entropy discontinuity in a weak
shock wave is quadratic in the pressure discontinuity when the effect of chiral
transport becomes sufficiently large. We also show that rarefaction shock
waves, which do not exist in usual nonchiral fluids, can appear in chiral
matter. The direction of shock wave propagation in a vorticity is found to be
completely determined by the direction of the vorticity and the chirality of
fermions. These features are exemplified by shock propagation in dense neutrino
matter in the hydrodynamic regime.Comment: 5 pages; v3: published versio
Primordial Hypermagnetic Fields and Triangle Anomaly
The high-temperature plasma above the electroweak scale GeV may
have contained a primordial hypercharge magnetic field whose anomalous coupling
to the fermions induces a transformation of the hypermagnetic energy density
into fermionic number. In order to describe this process, we generalize the
ordinary magnetohydrodynamical equations to the anomalous case. We show that a
not completely homogeneous hypermagnetic background induces fermion number
fluctuations, which can be expressed in terms of a generic hypermagnetic field
configuration. We argue that, depending upon the various particle physics
parameters involved in our estimate (electron Yukawa coupling, strength of the
electroweak phase transition) and upon the hypermagnetic energy spectrum,
sizeable matter-antimatter fluctuations can be generated in the plasma. These
fluctuations may modify the predictions of the standard Big Bang
nucleosynthesis (BBN). We derive constraints on the magnetic fields from the
requirement that the homogeneous BBN is not changed. We analyse the influence
of primordial magnetic fields on the electroweak phase transition and show that
some specific configurations of the magnetic field may be converted into net
baryon number at the electroweak scale.Comment: Latex, 53 pages, 8 eps figure
- …