5 research outputs found
Dark Matter and Dark Energy from a single scalar field and CMB data
Axions are likely to be the Dark Matter (DM) that cosmological data require.
They arise in the Peccei Quinn solution of the strong CP problem. In a previous
work we showed that their model has a simple and natural generalization which
yields also Dark Energy (DE), in fair proportions, without tuning any
parameter: DM and DE arise from a single scalar field and are weakly coupled in
the present era. In this paper we extend the analysis of this dual-axion
cosmology and fit it to WMAP data, by using a Markov chain technique. We find
that LCDM, dynamical DE with a SUGRA potential, DE with a SUGRA potential and a
constant DE-DM coupling, as well as the dual-axion model with a SUGRA
potential, fit data with a similar accuracy. The best-fit parameters are
however fairly different, although consistency is mostly recovered at the
2-sigma level. A peculiarity of the dual-axion model with SUGRA potential is to
cause more stringent constraints on most parameters and to favor high values of
the Hubble parameter.Comment: 34 pages, 15 figures, replaced with accepted versio
Dark Matter & Dark Energy from a single scalar field: CMB spectrum and matter transfer function
The dual axion model (DAM), yielding bot DM and DE form a PQ-like scalar
field solving the strong CP problem, is known to allow a fair fit of CMB data.
Recently, however, it was shown that its transfer function exhibits significant
anomalies, causing difficulties to fit deep galaxy sample data. Here we show
how DAM can be modified to agree with the latter data set. The modification
follows the pattern suggested to reconcile any PQ-like approach with gravity.
Modified DAM allows precise predictions which can be testable against future
CMB and/or deep sample data.Comment: 15 pages, 8 figures, accepted for publication in JCA
Perturbative QCD Forbidden Charmonium Decays and Gluonia
We address the problem of observed charmonium decays which should be
forbidden in perturbative QCD. We examine the model in which these decays
proceed through a gluonic component of the and the , arising
from a mixing of and glueball states. We give some bounds on the
values of the mixing angles and propose the study of the reaction, at GeV, as an independent test of the
model.Comment: 8pages, lateX, DFTT 64-9
Axion Emission by Magnetic-Field Induced Conversion of Longitudinal Plasmons
Magnetic fields mix axions with photons, allowing for the cyclotron process e
-> e + a by virtue of an intermediate plasmon even if axions do not couple to
electrons at tree level. The axion and longitudinal-plasmon dispersion
relations always cross for a certain wave number, leading to a resonant
enhancement of this process. Even then, however, it cannot quite compete with
the usual nucleon processes in a supernova core. The well-known axion window
10^{-5} eV < m_a < 10^{-2} eV remains open and axions may still constitute the
cosmic dark matter.Comment: 5 pages, REVTEX, 3 eps figs include