On the dynamics of a quadratic scalar field potential

We review the attractor properties of the simplest chaotic model of inflation, in which a minimally coupled scalar field is endowed with a quadratic scalar potential. The equations of motion in a flat Friedmann-Robertson-Walker universe are written as an autonomous system of equations, and the solutions of physical interest appear as critical points. This new formalism is then applied to the study of inflation dynamics, in which we can go beyond the known slow-roll formalism of inflation.Comment: 14 pages, 6 eps figures, matches version to appear in IJMP

Complex Hybrid Inflation and Baryogenesis

We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated to the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vev of the waterfall field, which is well constrained by diverse cosmological observations.Comment: 4 RevTex pages, no figures. Changes made in response to referee's comments; matches version published in Phys.Rev.Let

Inflation, dark matter and dark energy in the string landscape

We consider the conditions needed to unify the description of dark matter, dark energy and inflation in the context of the string landscape. We find that incomplete decay of the inflaton field gives the possibility that a single field is responsible for all three phenomena. By contrast, unifying dark matter and dark energy into a single field, separate from the inflaton, appears rather difficult.Comment: 4 pages RevTex4. Updated to include a toy model of reheating. Matches version accepted by Phys Rev Let

Triple unification of inflation, dark matter, and dark energy using a single field

We construct an explicit scenario whereby the same material driving inflation in the early Universe can comprise dark matter in the present Universe, using a simple quadratic potential. Following inflation and preheating, the density of inflaton/dark matter particles is reduced to the observed level by a period of thermal inflation, of a duration already invoked in the literature for other reasons. Within the context of the string landscape, one can further argue for a non-zero vacuum energy of this field, thus unifying inflation, dark matter and dark energy into a single fundamental field.Comment: 5 pages RevTeX with 3 figures incorporate

Dynamics of Scalar Field Dark Matter With a Cosh-like Potential

The dynamics of a cosmological model fueled by scalar field dark matter with a cosh-like potential plus a cosmological constant is investigated in detail. It is revealed that the late-time attractor is always the de Sitter solution, and that, depending on the values of the free parameters, the oscillating solution of the scalar field -- modeling cold dark matter -- mediates between some early stage (say, the radiation-dominated solution) and the accelerating de Sitter attractor.Comment: 9 pages, 17 figures, uses RevTe

Newtonian Collapse of Scalar Field Dark Matter

In this letter, we develop a Newtonian approach to the collapse of galaxy fluctuations of scalar field dark matter under initial conditions inferred from simple assumptions. The full relativistic system, the so called Einstein-Klein-Gordon, is reduced to the Schr\"odinger-Newton one in the weak field limit. The scaling symmetries of the SN equations are exploited to track the non-linear collapse of single scalar matter fluctuations. The results can be applied to both real and complex scalar fields.Comment: 4 pages RevTex4 file, 4 eps figure

Evolution of the Schr\"odinger--Newton system for a self--gravitating scalar field

Using numerical techniques, we study the collapse of a scalar field configuration in the Newtonian limit of the spherically symmetric Einstein--Klein--Gordon (EKG) system, which results in the so called Schr\"odinger--Newton (SN) set of equations. We present the numerical code developed to evolve the SN system and topics related, like equilibrium configurations and boundary conditions. Also, we analyze the evolution of different initial configurations and the physical quantities associated to them. In particular, we readdress the issue of the gravitational cooling mechanism for Newtonian systems and find that all systems settle down onto a 0--node equilibrium configuration.Comment: RevTex file, 19 pages, 26 eps figures. Minor changes, matches version to appear in PR

Observational constraints on dark energy model

The recent observations support that our universe is flat and expanding with acceleration. A quintessence model with a general relation between the quintessence potential and the quintessence kinetic energy was proposed to explain the phenomenon. The dark energy potential includes both the hyperbolic and the double exponential potentials. We analyze this model in detail by using the recent supernova and the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations. For a flat universe dominated by a dark energy with constant $\omega$ which is a special case of the general model, we find that $\Omega_{\rm m0}=0.30^{+0.06}_{-0.08}$ and $\omega_{\rm Q}\le -0.82$, and the turnaround redshift $z_{\rm T}$ when the universe switched from the deceleration phase to the acceleration phase is $z_{\rm T}=0.65$. For the general model, we find that $\Omega_{\rm m0}\sim 0.3$, $\omega_{\rm Q0}\sim -1.0$, $\beta\sim 0.5$ and $z_{\rm T}\sim 0.67$. A model independent polynomial parameterization is also considered, the best fit model gives $\Omega_{\rm m0}=0.40\pm 0.14$, $\omega_{\rm Q0}=-1.4$ and $z_{\rm T}=0.37$.Comment: 10 pages, 9 figures, update refererences, use ws-ijmpd style, use new supernova data and add model independent analysis. The updated paper also use a new method, fitting the WMAP data, main results remain unchanged. V4: more references added, accepted for publication in Int. J. Mod. Phys.

Galactic Collapse of Scalar Field Dark Matter

We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations and phenomenological studies in galaxies.Comment: 4 pages, 3 figue