20,640 research outputs found
Resolving the Inflationary Power Spectrum
Recently there have been differing viewpoints on how to evaluate the
curvature power spectrum generated during inflation. In a series of papers by
some authors it has been argued that the renormalization scheme adopted for the
inflaton field phi(x) to make finite should also be applied to
|phi_k|^2. But this then modifies the curvature power spectrum in a non-trivial
way. On the other hand, others have criticized this approach and suggested
alternatives, which have been further countered by the original authors. We
discuss these differing viewpoints and indicate inconsistencies in both
approaches. We then resolve the issue by showing why the standard expression,
without any non-trivial regularization, is still valid.Comment: To appear in the proceedings of The 10th International Symposium on
Cosmology and Particle Astrophysics (CosPA2013
Current Status of Warm Inflation
Warm inflation is an inflationary scenario in which a thermal bath coexists
with the inflaton during inflation. This is unlike standard cold inflation in
which the Universe is effectively devoid of particles during inflation. The
thermal bath in warm inflation is maintained by the dissipation of the
inflaton's energy through its couplings to other fields. Many models of warm
inflation have been proposed and their predictions have been compared with
cosmological data. Certain models of inflation that are disallowed in the
context of cold inflation by the data are allowed in the warm inflationary
scenario, and vice versa.Comment: 9 pages, 3 figures; Slightly longer version of a brief review talk at
the 18th Lomonosov Conference on Elementary Particle Physics at Moscow State
University, August 24-30, 201
On weakly tight families
Using ideas from Shelah's recent proof that a completely separable maximal
almost disjoint family exists when , we construct a
weakly tight family under the hypothesis \s \leq \b < {\aleph}_{\omega}. The
case when \s < \b is handled in \ZFC and does not require \b <
{\aleph}_{\omega}, while an additional PCF type hypothesis, which holds when
\b < {\aleph}_{\omega} is used to treat the case \s = \b. The notion of a
weakly tight family is a natural weakening of the well studied notion of a
Cohen indestructible maximal almost disjoint family. It was introduced by
Hru{\v{s}}{\'a}k and Garc{\'{\i}}a Ferreira \cite{Hr1}, who applied it to the
Kat\'etov order on almost disjoint families
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