Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Effect of alpha' Corrections in String Gas Cosmology   In the Brandenberger-Vafa scenario of string gas cosmology, the Universe
starts as a small torus of string length dimension filled with a hot gas of
strings. In such extreme conditions, in addition to the departure from Einstein
gravity which is due to the dilaton, one expects higher curvature corrections
to be relevant. Motivated by this fact, we study the effect of the leading
alpha'^3 corrections in type IIB string theory for this scenario. Within the
assumptions of: weak coupling, adiabatic evolution and thermodynamical
equilibrium, we perturbatively solved the corresponding equations of motion in
two different cases: (i) the isotropic case which is governed by a single scale
factor and (ii) the anisotropic case given by two different scale factors. In
the first case, we consider two regimes (ia) The Hagedorn regime where the
string gas equation of state is that of pressureless dust, and (ib) the
radiation regime. In the second case, (ii), we only considered a radiation-like
equation of state. We found that the inclusion of alpha' corrections affects
the scale factor(s) in opposite way in the Hagedorn and in the radiation
regimes, acting as a driving force for the first one and a damping force for
the second one. This effect is small for reasonable initial conditions and it
is only observed at early times. Morever it is bigger in the Hagedorn regime
than in the radiation regime. We also analyzed the fixed points of the system.
We found that there exists a stable dS fixed point, which does not exist when
the corrections are neglected.

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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat