Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Primordial Spectrum of Gauge Fields from Inflation   We show that conformal invariance of gauge fields is naturally broken in
inflation, having as a consequence amplification of gauge fields. The resulting
spectrum of the field strength is approximately B_L ~ L^(-1), where L is the
relevant coherence scale. One realisation of our scenario is scalar
electrodynamics with a scalar whose mass is large enough to evade observational
constraints - the obvious candidates being supersymmetric partners of the
standard-model fermions. Our mechanism also leads naturally to amplification of
the standard-model Z-boson field due to its coupling to the electroweak Higgs
field. At preheating, the spectrum of the Z field is transferred to the
hypercharge field, which remains frozen in the plasma and is converted into a
magnetic field at the electroweak phase transition. With a reasonable model of
field evolution one obtains a magnetic field strength of the order of
$10^{-29}$ Gauss on a scale of 100 pc, the size of the largest turbulent eddy
in a virialised galaxy. Resonant amplification in preheating can lead to
primordial fields as large as $10^{-24}$ Gauss, consistent with the seed field
required for the galactic dynamo mechanism.

28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg