IFIBA   22255
INSTITUTO DE FISICA DE BUENOS AIRES
Unidad Ejecutora - UE
artículos
Título:
Primordial magnetic helicity from stochastic electric currents
Autor/es:
ESTEBAN CALZETTA; ALEJANDRA KANDUS
Revista:
PHYSICAL REVIEW D - PARTICLE AND FILDS
Editorial:
APS
Referencias:
Lugar: Ridge; Año: 2014 vol. 89 p. 1 - 32
ISSN:
0556-2821
Resumen:
We study the possibility that primordial magnetic fields generated in
the transition between inflation and reheating posses magnetic helicity,
HM.
The fields are induced by stochastic currents of scalar charged
particles created during the mentioned transition. We estimate the rms
value of the induced magnetic helicity by computing different four-point
scalar quantum electrodynamics Feynman diagrams. For any considered
volume, the magnetic flux across its boundaries is in principle not
null, which means that the magnetic helicity in those regions is gauge
dependent. We use the prescription given by Berger and Field and
interpret our result as the difference between two magnetic
configurations that coincide in the exterior volume. In this case, the
magnetic helicity gives only the number of magnetic links inside the
considered volume. We calculate a concrete value of HM
for large scales and analyze the distribution of magnetic defects as a
function of the scale. Those defects correspond to regular as well as
random fields in the considered volume. We find that the fractal
dimension of the distribution of topological defects is D=1/2.
We also study if the regular fields induced on large scales are
helical, finding that they are and that the associated number of
magnetic defects is independent of the scale. In this case, the fractal
dimension is D=0.
We finally estimate the intensity of fields induced at the horizon
scale of reheating and evolve them until the decoupling of matter and
radiation under the hypothesis of the inverse cascade of magnetic
helicity. The resulting intensity is high enough and the coherence
length long enough to have an impact on the subsequent process of
structure formation.