93 research outputs found
Coupled dark energy: a dynamical analysis with complex scalar field
The dynamical analysis for coupled dark energy with dark matter is presented,
where a complex scalar field is taken into account and it is considered in the
presence of a barothropic fluid. We consider three dark energy candidates:
quintessence, phantom and tachyon. The critical points are found and their
stabilities analyzed, leading to the three cosmological eras (radiation, matter
and dark energy), for a generic potential. The results presented here enlarge
the previous analyses found in the literature.Comment: 9 pages, version accepted for publication in EPJC. arXiv admin note:
text overlap with arXiv:1505.0324
Dynamical analysis for a vector-like dark energy
In this paper we perform a dynamical analysis for a vector field as a
candidate for the dark energy, in the presence of a barothropic fluid. The
vector is one component of the so-called cosmic triad, which is a set of three
identical copies of an abelian field pointing mutually in orthogonal
directions. In order to generalize the analysis, we also assumed the
interaction between dark energy and the barotropic fluid, with a
phenomenological coupling. Both matter and dark energy eras can be successfully
described by the critical points, indicating that the dynamical system theory
is a viable tool to analyze asymptotic states of such cosmological models.Comment: 6 pages, 3 figures, version to appear in EPJ
Cosmological tracking solution and the Super-Higgs mechanism
In this paper we argue that minimal supergravity with flat K\"ahler metric
and a power-law superpotential can relate the Super-Higgs mechanism for the
local spontaneous supersymmetry breaking and the cosmological tracking
solution, leading in turn to a late-time accelerated expansion of the universe
and alleviating the coincidence problem.Comment: 5 pages, 1 figure, minor corrections, to appear in EPJ
Fat brane, dark matter and localized kinetic terms in six dimensions
Extra dimensions (ED) have been used as attempts to explain several phenomena
in particle physics over the years. In this paper we investigate the role of an
abelian gauge field as mediator of the interaction between dark matter (DM) and
Standard Model (SM) particles, in a model with two flat and transverse ED
compactified on the chiral square. DM is confined in a thin brane, localized at
the origin of the chiral square, while the SM is localized in a finite width
brane, lying in the opposite corner of the square. A brane-localized kinetic
term is present in the DM brane, while in the fat brane it is not allowed. In
this model the kinetic mixing is not required because we assume that the SM
particles couple to the mediator through their charges, while DM couples
to it via a dark charge. Assuming a complex scalar field as DM candidate it is
possible to obtain the observed DM relic abundance and avoid direct detection
constraints for some parameter choices.Comment: 12 pages, 6 figures, 2 tables, references added, version accepted for
publication in EPJ
Dark photon dark matter and fast radio bursts
The nature of dark matter (DM) is still a mystery that may indicate the
necessity for extensions of the Standard Model (SM). Light dark photons (DP)
may comprise partially or entirely the observed DM density and existing limits
on the DP DM parameter space arise from several cosmological and astrophysical
sources. In the present work we investigate DP DM using cosmic transients,
specifically fast radio bursts (FRBs). The observed time delay of radio photons
with different energies have been used to constrain the photon mass or the Weak
Equivalence Principle, for example. Due to the mixing between the visible and
the DP, the time delay of photons from these cosmic transients, caused by free
electrons in the intergalactic medium, can change and impact those constraints
from FRBs. We use five detected FRBs and two associations of FRBs with
gamma-ray bursts to investigate the correspondent variation on the time delay
caused by the presence of DP DM. The result is virtually independent of the FRB
used and this variation is very small, considering the still allowed DP DM
parameter space, not jeopardizing current bounds on other contributions of the
observed time delay.Comment: 9 pages, 3 figures, 1 table, references added, version accepted for
publication in EPJ
Interacting Dark Energy: Possible Explanation for 21-cm Absorption at Cosmic Dawn
A recent observation points to an excess in the expected 21-cm brightness
temperature from cosmic dawn. In this paper, we present an alternative
explanation of this phenomenon, an interaction in the dark sector. Interacting
dark energy models have been extensively studied recently and there is a whole
variety of such in the literature. Here we particularize to a specific model in
order to make explicit the effect of an interaction.Comment: 5 pages, 2 figures. Discussion improved, new references, conclusions
unchanged. Accepted in EPJ
- …