Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Primordial magnetic fields, anomalous isocurvature fluctuations and Big
  Bang nucleosynthesis   We show that the presence of primordial stochastic (hypercharge) magnetic
fields before the electroweak (EW) phase transition induces isocurvature
fluctuations (baryon number inhomogeneities). Depending on the details of the
magnetic field spectrum and on the particle physics parameters (such as the
strength of the EW phase transition and electron Yukawa couplings) these
fluctuations may survive until the Big Bang nucleosynthesis (BBN). Their
lenghtscale may exceed the neutron diffusion length at that time, while their
magnitude can be so large that sizable antimatter domains are present. This
provides the possibility of a new type of initial conditions for
non-homogeneous BBN or, from a more conservative point of view, stringent
bounds on primordial magnetic fields.

37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom