arXiv subjects

César A. Valenzuela-Toledo

Publications and source records attributed to César A. Valenzuela-Toledo.

23 records · Page 2Linked to original sources

arXiv2019

$p$-form quintessence: exploring dark energy of $p-$forms coupled to a scalar field

We consider a model based on $p-$form kinetic Lagrangians in the context of dark energy. The Lagrangian of the model is built with kinetic terms of the field strength for each $p$-form coupled to a scalar field $ϕ$ through a kinetic function. We assume that this scalar field is responsible for the present accelerated expansion of the Universe. Since we are interested in cosmological applications, we specialize the analysis to a 4-dimensional case, using an anisotropic space-time. By studying the dynamical equations, we investigate the evolution of the dark energy density parameter, the effective equation of state and the shear induced by the anisotropic configuration.

gr-qc↗

arXiv2019

Correlation functions of sourced gravitational waves in inflationary scalar vector models. A symmetry based approach

We use conformal symmetry to constrain the shape of inflationary correlators in the presence of long-lived vector field perturbations. Applying conformal Ward identities, we derive general expressions, up to amplitudes and normalization factors, for the two and three point correlators in the presence of vector fields mediated by the interaction $f(ϕ)\left(F_{μν}F^{μν}+α\tilde{F}_{μν}F^{μν}\right)$, where $f(ϕ)$ is a suitable coupling function between the scalar and the vector field. The previous interaction allows for isotropy and parity symmetry breaking and is consistent with super horizon conformal symmetry. As an application of the conformal field theory techniques followed here, we evaluate the mixed tensor-scalar $\langle γζ\rangle$ and tensor-scalar-scalar $\langle γζζ\rangle$ correlators which are interesting to look for parity violating effects related with chiral gravitational waves. Finally, we derive consistency relations for the three point correlators obtained.

gr-qc↗

arXiv2019

Anisotropic inflation with coupled $\boldsymbol{p}$-forms

We study the cosmology in the presence of arbitrary couplings between $p$-forms in 4-dimensional space-time for a general action respecting gauge symmetry and parity invariance. The interaction between 0-form (scalar field $ϕ$) and 3-form fields gives rise to an effective potential $V_{\rm eff}(ϕ)$ for the former after integrating out the contribution of the latter. We explore the dynamics of inflation on an anisotropic cosmological background for a coupled system of 0-, 1-, and 2-forms. In the absence of interactions between 1- and 2-forms, we derive conditions under which the anisotropic shear endowed with nearly constant energy densities of 1- and 2-forms survives during slow-roll inflation for an arbitrary scalar potential $V_{\rm eff}(ϕ)$. If 1- and 2-forms are coupled to each other, we show the existence of a new class of anisotropic inflationary solutions in which the energy density of 2-form is sustained by that of 1-form through their interactions. Our general analytic formulas for the anisotropic shear are also confirmed by the numerical analysis for a concrete inflaton potential.

gr-qc↗

arXiv2019

Anisotropic $2$-form dark energy

We study the dynamics of dark energy in the presence of a 2-form field coupled to a canonical scalar field $ϕ$. We consider the coupling proportional to $e^{-μϕ/M_{\rm pl}} H_{αβγ}H^{αβγ}$ and the scalar potential $V(ϕ) \propto e^{-λϕ/M_{\rm pl}}$, where $H_{αβγ}$ is the 2-form field strength, $μ, λ$ are constants, and $M_{\rm pl}$ is the reduced Planck mass. We show the existence of an anisotropic matter-dominated scaling solution followed by a stable accelerated fixed point with a non-vanishing shear. Even if $λ\geq {\cal O}(1)$, it is possible to realize the dark energy equation of state $w_{\rm DE}$ close to $-1$ at low redshifts for $μ\gg λ$. The existence of anisotropic hair and the oscillating behavior of $w_{\rm DE}$ are key features for distinguishing our scenario from other dark energy models like quintessence.

hep-th↗

arXiv2017

de Sitter symmetries and inflationary correlators in parity violating scalar-vector models

In this paper we use conformal field theory techniques to constrain the form of the correlations functions of an inflationary scalar-vector model described by the interaction term $f_1(ϕ)F_{μν}F^{μν} + f_2(ϕ)\tilde{F}_{μν}F^{μν}$. We use the fact that the conformal group is the relevant symmetry group acting on super horizon scales in an inflationary de Sitter background. As a result, we find that super horizon conformal symmetry, constraints the form of the coupling functions $f_1, f_2$ to be homogeneous functions of the same degree. We derive the general form of the correlators involving scalar and vector perturbations in this model and determine its squeezed limit scaling behaviour for super horizon scales. The approach followed here is useful to constraint the shape of scalar-vector correlators, and our results agree with recent literature on the subject, but don't allow us to determine amplitude factors of the correlators.

astro-ph.CO↗