Effects of discontinuities of the derivatives of the inflaton potential

We study the effects of a class of features of the inflaton potential, corresponding to discontinuties in its derivatives. We perform fully numerical calculations and derive analytical approximations for the curvature pertubations spectrum and the bispectrum which are in good agreement with the numerical results. The spectrum of primordial perturbations has oscillations around the scale $k_0$ which leaves the horizon at the time $\tau_0$ when the feature occurs, with the amplitude and phase of the oscillations determined by the size and the order of the discontinuity. The large scale bispectrum in the squeezed and equilateral limits have a very similar form and are linearly suppressed. Both in the squeezed and equilateral small scale limit the bispectrum has an oscillatory behavior whose phase depends on the parameters determining the discontinuity, and whose amplitude is inversely proportional to the scale. Given the generality of this class of features they could be used to model or classify phenomenologically different types of non Gaussian features encountered in observational data such as the cosmic microwave background radiation or large scale structure.Comment: 26 pages, 22 figures, version accepted by EPJ

CMB anomalies and the effects of local features of the inflaton potential

Recent analysis of the WMAP and Planck data have shown the presence of a dip and a bump in the spectrum of primordial perturbations at the scales $k=0.002$ Mpc${}^{-1}$ and $k=0.0035$ Mpc${}^{-1}$ respectively. We analyze for the first time the effects a local feature in the inflaton potential to explain the observed deviations from scale invariance in the primordial spectrum. We perform a best fit analysis of the cosmic microwave background (CMB) radiation temperature and polarization data. The effects of the features can improve the agreement with observational data respect to the featureless model. The best fit local feature affects the primordial curvature spectrum mainly in the region of the bump, leaving the spectrum unaffected on other scales.Comment: 18 pages, 8figures, published in EPJ

11-Dimensional Supergravity Compactified on Calabi-Yau Threefolds

We consider generic features of eleven dimensional supergravity compactified down to five dimensions on an arbitrary Calabi-Yau threefold.Comment: TeX, harvmac, 8 pg

El proceso de objetivación del concepto de parábola desde el uso de artefactos

Presentó en este encuentro algunos resultados de la investigación “La objetivación del concepto de parábola desde el uso de artefactos”. Estos resultados nos muestran cómo los artefactos son constituyentes en el proceso de objetivación del concepto de parábola. Para ello, explicitamos, en una primera parte, la importancia que desde la Teoría de la Actividad se le ha dado al carácter mediatizado del pensamiento; seguidamente mostramos, a partir de los diferentes episodios, cómo los artefactos culturales, en el sentido de Radford (2008) se convierten en constituyentes en el proceso de objetivación del concepto de parábola. Así, consideramos que la manera como un sujeto llega a pensar y a conocer un objeto depende de los significados culturales producidos, de las interpretaciones propias, de las formas de acercase al objeto, por medio de la actividad misma y siempre mediada por artefactos

The Elementary Particles as Quantum Knots in Electroweak Theory

We explore a knot model of the elementary particles that is compatible with electroweak physics. The knots are quantized and their kinematic states are labelled by $D^j_{mm'}$, irreducible representations of $SU_q(2)$, where j = N/2, m = w/2, m' = (r+1)/2 and (N,w,r) designate respectively the number of crossings, the writhe, and the rotation of the knot. The knot quantum numbers (N,w,r) are related to the standard isotopic spin quantum numbers $(t,t_3,t_0)$ by $(t=N/6,t_3=-w/6,t_0=-(r+1)/6)$, where $t_0$ is the hypercharge. In this model the elementary fermions are low lying states of the quantum trefoil (N=3) and the gauge bosons are ditrefoils (N=6). The fermionic knots interact by the emission and absorption of bosonic knots. In this framework we have explored a slightly modified standard electroweak Lagrangian with a slightly modified gauge group which agrees closely but not entirely with standard electroweak theory.Comment: 29 pages; LaTex fil