arXiv subjects

Alejandro Pérez Rodríguez

Publications and source records attributed to Alejandro Pérez Rodríguez.

5 recordsLinked to original sources

arXiv2026

Classical and quantum evolution of inflationary fluctuations

We compare the correlation functions of inflationary perturbations computed either with quantum or classical dynamics. Even if they are enforced to agree at a specific time during inflation, classical and quantum correlations will differ at the end of inflation, provided that interactions are relevant. The difference between the results of the classical and quantum computations is exponentially sensitive to the number of e-folds elapsed from the time of agreement. We illustrate this finding with the tree-level bispectrum of the primordial curvature fluctuation and the one-loop power spectrum of tensor modes. We also show that classical evolution from a finite time does not imply the appearance of poles in the scalar bispectrum.

hep-th↗

arXiv2025

Intrinsic non-Gaussianity of ultra slow-roll inflation

We study the non-Gaussian tail of the curvature fluctuation, $ζ$, in an inflationary scenario with a transient ultra slow-roll phase that generates a localized large enhancement of the spectrum of $ζ$. To do so, we implement a numerical procedure that provides the probability distribution of $ζ$ order by order in perturbation theory. The non-Gaussianities of $ζ$ can be shown to arise from its non-linear relation to the inflaton fluctuations and from the intrinsic non-Gaussianities of the latter, which stem from its self interactions. We find that intrinsic non-Gaussianities, which have often been ignored to estimate the abundance of primordial black holes in this kind of scenario, are important. The relevance of the intrinsic contribution depends on the rapidity with which the transient ultra slow-roll phase occurs, as well as on its duration. Our method cannot be used accurately when the perturbative in-in formalism fails to apply, highlighting the relevance of developing fully non-perturbative approaches to the problem.

astro-ph.CO↗

arXiv2024

Non-Gaussian tails without stochastic inflation

We show, both analytically and numerically, that non-Gaussian tails in the probability density function of curvature perturbations arise in ultra-slow-roll inflation from the $δN$ formalism, without invoking stochastic inflation. Previously reported discrepancies between both approaches are a consequence of not correctly accounting for momentum perturbations. Once they are taken into account, both approaches agree to an excellent degree. The shape of the tail depends strongly on the phase space of inflation.

astro-ph.CO↗

arXiv2024

Monomial warm inflation revisited

We revisit the idea that the inflaton may have dissipated part of its energy into a thermal bath during inflation, considering monomial inflationary potentials and three different forms of dissipation rate. Using a numerical Fokker-Planck approach to describe the stochastic dynamics of inflationary fluctuations, we confront this scenario with current bounds on the spectrum of curvature fluctuations and primordial gravitational waves. We also obtain purely analytical approximations that improve over previously used ones in the small dissipation regime for the amplitude of the spectrum and its tilt. We show that only our numerical Fokker-Planck method is accurate, fast and precise enough to test these models against current data. We advocate its use in future studies of warm inflation. We also apply the stochastic inflation formalism to this scenario, finding that the resulting spectrum is the same as the one obtained with standard perturbation theory. We discuss the origin and convenience of using a commonly implemented large thermal correction to the primordial spectrum and the implications of such a term for a specific scenario. Improved bounds on the scalar spectral index will further constrain warm inflation in the near future.

astro-ph.CO↗

arXiv2024

Primordial black holes and gravitational waves from dissipation during inflation

We study the generation of a localized peak in the primordial spectrum of curvature perturbations from a transient dissipative phase during inflation, leading to a large population of primordial black holes. The enhancement of the power spectrum occurs due to stochastic thermal noise sourcing curvature fluctuations. We solve the stochastic system of Einstein equations for many realizations of the noise and obtain the distribution for the curvature power spectrum. We then propose a method to find its expectation value using a deterministic system of differential equations. In addition, we find a single stochastic equation whose analytic solution helps to understand the main features of the spectrum. Finally, we derive a complete expression and a numerical estimate for the energy density of the stochastic background of gravitational waves induced at second order in perturbation theory. This includes the gravitational waves induced during inflation, during the subsequent radiation epoch and their mixing. Our scenario provides a novel way of generating primordial black hole dark matter with a peaked mass distribution and a detectable stochastic background of gravitational waves from inflation.

astro-ph.CO↗