Arquivo da tag: papers

ArXiv & papers highlights, vol. 5

Preheating in bubble collisions: “Author(s): Jun Zhang and Yun-Song Piao
In a landscape with metastable minima, the bubbles will inevitably nucleate. We show that when the bubbles collide, due to the dramatic oscillation of the field at the collision region, the energy deposited in the bubble walls can be efficiently released by the explosive production of the particles….
[Phys. Rev. D 82, 043507] Published Thu Aug 05, 2010”

Inflation from supersymmetric quantum cosmology: “Author(s): J. Socorro and Marco D’Oleire
We derive a special scalar field potential using the anisotropic Bianchi type I cosmological model from canonical quantum cosmology under determined conditions in the evolution to anisotropic variables β_{±} . In the process, we obtain a family of potentials that has been introduced by hand in the…
[Phys. Rev. D 82, 044008] Published Thu Aug 05, 2010”

Two pieces of folklore in the AdS/CFT duality: “Author(s): Kengo Maeda, Makoto Natsuume, and Takashi Okamura
In the AdS/CFT duality, it is often said that a local symmetry in a bulk theory corresponds to a global symmetry in the corresponding boundary theory, but the global symmetry can become local when one couples with an external source. As a result, the Gubser-Klebanov-Polyakov-Witten relation gives a …
[Phys. Rev. D 82, 046002] Published Thu Aug 05, 2010”

Inflation in models with conformally coupled scalar fields: An application to the noncommutative spectral action: “Author(s): Michel Buck, Malcolm Fairbairn, and Mairi Sakellariadou
Slow-roll inflation is studied in theories where the inflaton field is conformally coupled to the Ricci scalar. In particular, the case of Higgs field inflation in the context of the noncommutative spectral action is analyzed. It is shown that while the Higgs potential can lead to the slow-roll cond…
[Phys. Rev. D 82, 043509] Published Fri Aug 06, 2010”

CMB in a box: Causal structure and the Fourier-Bessel expansion: “Author(s): L. Raul Abramo, Paulo H. Reimberg, and Henrique S. Xavier
This paper makes two points. First, we show that the line-of-sight solution to cosmic microwave anisotropies in Fourier space, even though formally defined for arbitrarily large wavelengths, leads to position-space solutions which only depend on the sources of anisotropies inside the past light cone…
[Phys. Rev. D 82, 043510] Published Fri Aug 06, 2010”

Naturality, unification, and dark matter: “Author(s): Kimmo Kainulainen, Kimmo Tuominen, and Jussi Virkajärvi
We consider a model where electroweak symmetry breaking is driven by technicolor dynamics with minimal particle content required for walking coupling and saturation of global anomalies. Furthermore, the model features three additional Weyl fermions singlet under technicolor interactions, two of whic…
[Phys. Rev. D 82, 043511] Published Fri Aug 06, 2010”

TeV scale dark matter and electroweak radiative corrections: “Author(s): Paolo Ciafaloni and Alfredo Urbano
Recent anomalies in cosmic rays data, namely, from the PAMELA Collaboration, can be interpreted in terms of TeV scale decaying/annihilating dark matter. We analyze the impact of radiative corrections coming from the electroweak sector of the standard model on the spectrum of the final products at th…
[Phys. Rev. D 82, 043512] Published Fri Aug 06, 2010”

Dark energy equation of state and cosmic topology. (arXiv:1008.0832v1 [astro-ph.CO]): ”

The immediate observational consequence of a non-trivial spatial topology of
the Universe is that an observer could potentially detect multiple images of
radiating sources. In particular, a non-trivial topology will generate pairs of
correlated circles of temperature fluctuations in the anisotropies maps of the
cosmic microwave background (CMB), the so-called circles-in-the-sky. In this
way, a detectable non-trivial spatial topology may be seen as an observable
attribute, which can be probed through the circles-in-the-sky for all locally
homogeneous and isotropic universes with no assumptions on the cosmological
dark energy (DE) equation of state (EOS) parameters. We show that the knowledge
of the spatial topology through the circles-in-the-sky offers an effective way
of reducing the degeneracies in the DE EOS parameters. We concretely illustrate
the topological role by assuming, as an exanple, a Poincar\'{e} dodecahedral
space topology and reanalyzing the constraints on the parameters of a specific
EOS which arise from the supernovae type Ia, baryon acoustic oscillations and
the CMB plus the statistical topological contribution.

Unified Dark Matter Scalar Field Models. (arXiv:1008.0614v1 [astro-ph.CO]): ”

In this work we analyze and review cosmological models in which the dynamics
of a single scalar field accounts for a unified description of the Dark Matter
and Dark Energy sectors, dubbed Unified Dark Matter (UDM) models. In this
framework, we consider the general Lagrangian of k-essence, which allows to
find solutions around which the scalar field describes the desired mixture of
Dark Matter and Dark Energy. We also discuss static and spherically symmetric
solutions of Einstein’s equations for a scalar field with non-canonical kinetic
term, in connection with galactic halo rotation curves

The propagator in polymer quantum field theory. (arXiv:1007.5500v1 [gr-qc]): ”

We study free scalar field theory on flat spacetime using a background
independent (polymer) quantization procedure. Specifically we compute the
propagator using a method that takes the energy spectrum and position matrix
elements of the harmonic oscillator as inputs. We obtain closed form results in
the infrared and ultraviolet regimes that give Lorentz invariance violating
dispersion relations, and show suppression of propagation at sufficiently high

Eternal Inflation with Liouville Cosmology. (arXiv:1007.5499v1 [hep-th]): ”

We present a concrete holographic realization of the eternal inflation and
its census taker in (1+1) dimensional Liouville gravity by applying the FRW/CFT
philosophy proposed by Freivogel, Sekino, Susskind and Yeh (FSSY). The dual
boundary theory is nothing but the old matrix model describing the
two-dimensional Liouville gravity coupled with minimal model matter fields. In
Liouville gravity, the flat Minkowski space or even the AdS space will decay
into the dS space, which is in stark contrast with higher dimensional theories,
but the spirit of the FSSY conjecture applies with only minimal modification.
We investigate the classical geometry as well as some correlation functions to
support our claim. We also study an analytic continuation to the time-like
Liouville theory to discuss possible applications in (1+3) dimensional
cosmology along with the original FSSY conjecture, where the boundary theory
involves the time-like Liouville theory. We show that the decay rate in the
$(1+3)$ dimension is more suppressed due to the quantum gravity correction of
the boundary theory.