Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of the curvature perturbation during and after multi-field
  inflation   We study the evolution of the curvature perturbation on the super-horizon
scales starting from the inflationary epoch until there remains only a single
dynamical degree of freedom, presureless matter, in the universe. We consider
the cosmic inflation driven by a multiple number of the inflaton fields, which
decay into both radiation and pressureless matter components. We present a
complete set of the exact background and perturbation equations which describe
the evolution of the universe throughout its history. By applying these
equations to the simple but reasonable model of multi-field chaotic inflation,
we explicitly show that the total curvature perturbation is continuously
varying because of the non-adiabatic components of the curvature perturbation
generated by the multiple inflaton fields throughout the whole evolution of the
universe. We also provide an useful analytic estimation of the total as well as
matter and radiation curvature perturbations, assuming that matter is
completely decoupled from radiation from the beginning. The resulting
isocurvature perturbation between matter and radiation is at most sub-percent
level when the masses of the inflaton fields are distributed between
$10^{-6}m_{pl}$ and $10^{-5}m_{pl}$. We find that this result is robust unless
we use non-trivial decay rates, and that thus, in general, it is hard to obtain
large matter-radiation isocurvature perturbation. Also, by using the
$\delta{N}$ formalism, we point out that the inflationary calculation,
especially when involving multiple inflaton fields, is likely to lose the
potentially important post-inflationary evolution which can modify the
resulting curvature perturbation.

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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs