Theoretical and observational characterization of primordial scales and symmetries

Abstract

In this thesis, theoretical aspects of observables thrown by cosmic inflation were studied. In the first work, hypothetical feature correlations were studied in the inflationary scalar spectrum with features in the tensorial spectrum, with an explicit relationship between both at the limit of the sharp features. In particular, the anomaly in the scalar spectrum around l = 23 was taken as an example, where the impact of it on the tensorial spectrum was studied. The first slow-roll parameter, Epsilon, might suppress those possible deviations to the scale invariance in the tensorial spectrum. In the second work, it was found how to generate physical modes in the infrared limit in scenarios where the curvature perturbations evolve outside the horizon. They obey remaining symmetries that satisfy curvature modes in the infrared limit, called by other authors, shift-symmetries. Particularly, as a result of this limit, pre-existing relationships in the literature (violations of the Maldacena consistency relation) could be recovered without resorting to standard in-in formalism for the calculation quantum interactions, or Schwinger-Kelldish interactions. In the third work, the gravitational effect of the adiabatic curvature modes on an inertial observer was studied, for which the conformal Fermi coordinates (CFC) associated with this observer were used. In this framework, we investigated the limits of the testability on the modes of curvature in the infrared limit, particularly, considered two inflationary scenarios of great phenomenological importance using CFCs; ultra slow-roll (USR) and slow-roll (SR) inflation. In both, it was found that the amount of local non-Gaussianity observed by an inertial observer at first order is zero. Additionally, a connection was found between the coordinate transformations induced by the CFCs and the coordinate transformations generated by elements of the conformal group in a de Sitter space. Finally, beams associated with the 40GHz band for the CLASS telescope were characterized, they were modeled at the level of 1% above the intrinsic noise floor of the detectors, eliminating systematic calibration effects through a pseudoanalytic deconvolution of the calibration source used(the Moon), in the regime of axially symmetric beams and sources. Finally, its window function was obtained within the range of multiples 0 <l <250 at the level of 1%.