Novel vacuum conditions in inflationary collapse models

Abstract

Within the framework of inflationary models that incorporate a spontaneous reduction of the wave function for the emergence of the seeds of cosmic structure, we study the effects on the primordial scalar power spectrum by choosing a novel initial quantum state that characterizes the perturbations of the inflaton. Specifically, we investigate under which conditions one can recover an essentially scale free spectrum of primordial inhomogeneities when the standard Bunch-Davies vacuum is replaced by another one that minimizes the renormalized stress-energy tensor via a Hadamard procedure. We think that this new prescription for selecting the vacuum state is better suited for the self-induced collapse proposal than the traditional one in the semiclassical gravity picture. We show that the parametrization for the time of collapse, considered in previous works, is maintained. Also, we obtain an angular spectrum for the CMB temperature anisotropies consistent with the one that best fits the observational data. Therefore, we conclude that the collapse mechanism might be of a more fundamental character than previously suspected.Comment: 17 pages, 2 figures. Extended and revised version. To appear in Physics Letters

Emergent universe revisited through the CSL theory

“…To finish this Introduction, let us mention that in some previous works [225,229,230], where a spontaneous collapse of the wave function was implemented during a phase of slow-roll inflation, certain features on the low multipoles of the CMB were analyzed as consequence of the collapse. On the other hand, recently in [160] the emergent universe model, originally put forward in [124,127], was analyzed and it was shown that the superinflation phase (a characteristic shared by all emergent universe models) could be responsible for part of the anomaly in the low multipoles of the CMB; in particular, for the observed lack of power at large angular scales.…”

Emergent universe revisited through the CSL theory

“…To finish this Introduction, let us mention that in some previous works [230,234,235], where a spontaneous collapse of the wave function was implemented during a phase of slowroll inflation, certain features on the low multipoles of the CMB were analyzed as consequence of the collapse. On the other hand, recently in [164] the emergent universe model, originally put forward in [128,131], was analyzed and it was shown that the super-inflation phase (a characteristic shared by all emergent universe models) could be responsible for part of the anomaly in the low multipoles of the CMB; in particular, for the observed lack of power at large angular scales.…”

Comparación de las predicciones de cosmologías alternativas al modelo cosmológico estándar con datos del fondo cósmico de radiación

“…Por lo tanto, de ser detectados modos de polarización del FCR correspondiente a ondas gravitacionales primordiales, es necesario abandonar la aproximación semiclásica y llevar a cabo la cuantización a través de la variable de Mukhanov-Sasaki. Sin embargo, aún no ha habido detección observacional confirmada de tales modos(BICEP2/Keck Collaboration et al, 2015; Planck Collaboration et al, 2017).El cálculo del espectro primordial de fluctuaciones en el contexto de la hipótesis del colapso autoinducido utilizando la variable de Mukhanov-Sasaki ha sido realizado por Diez-Tejedor et al (2012) para los esquemas de colapso y porBengochea & León (2017) para CSL.…”