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J. G. Rodrigues

Publications and source records attributed to J. G. Rodrigues.

13 recordsLinked to original sources
arXiv2026

ACT DR6+Planck impact on inflation with non-zero vacuum expectation value and the post-inflationary behavior

The impact of the most recent cosmic microwave background (CMB) data from the Atacama Cosmology Telescope (ACT) is studied for a model of cosmic inflation which predicts a non-zero vacuum expectation value (VEV) $M$ for a large-field regime. Since lower values of $M$ are compatible with the higher spectral index $n_s$ provided by the ACT+Planck joint analysis, we establish new limits on this parameter while also considering further CMB data from the latest BICEP/Keck Array release for CMB polarization modes. We find $\log_{10}M/M_{Pl}=-2.5^{+1.1}_{-1.3}$ at 68\% confidence level, compatible with $M/M_{Pl}\simeq 0.003$, which is interesting for post-inflationary processes, such as preheating. We conduct a lattice simulation for the inflaton field for the first few e-folds, as the model is compatible with the production of relics such as oscillons, which are possible candidates as sources of gravitational waves and primordial black holes. We find that the model indeed produces localized, quasi-spherical structures compatible with oscillons, which might lead to signatures detectable by future experiments. However, in agreement with recent works, we find that although the abundance of gravitational waves that could be generated in this regime has an amplitude well within the sensitivities of these detectors, the frequency range is on the GHz limit, away from the expected frequencies. Finally, we estimate the impact of a coupling of the type $y\phi\chi^2$ to the inflaton, in the realization of perturbative reheating, directly impacting the predictions of the model, as lower values of $M$ are consistent with both the entire allowed temperature range, and the limits imposed by BICEP/Keck Array+Planck+ACT.

astro-ph.CO↗
arXiv2025

Forecasting constraints on quintessential inflation from future generation of galaxy and CMB surveys

We investigate the constraining power of future CMB and galaxy surveys on models of quintessential inflation realized within the framework of $\alpha$-attractors. We analyze how these future datasets will probe the parameter space of $\alpha$-attractor quintessential inflation, specifically the inflationary potential parameters. Our results demonstrate that the synergy between CMB-S4, LiteBIRD, and Euclid can significantly tighten the bounds on the model parameters, achieving forecasted $1\sigma$ uncertainties of $\alpha=2\pm 0.17$, $n_s=0.965\pm 0.0014$, $\ln(10^{10}A_s)=3.0447\pm 0.0029$ for the CMB+GC$_{sp}$ case. This level of sensitivity will enable us to discriminate between different realizations of quintessential inflation and test the attractor behavior characteristic of these models.

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arXiv2025

Brazilian Report on Dark Matter 2024

One of the key scientific objectives for the next decade is to uncover the nature of dark matter (DM). We should continue prioritizing targets such as weakly-interacting massive particles (WIMPs), Axions, and other low-mass dark matter candidates to improve our chances of achieving it. A varied and ongoing portfolio of experiments spanning different scales and detection methods is essential to maximize our chances of discovering its composition. This report paper provides an updated overview of the Brazilian community's activities in dark matter and dark sector physics over the past years with a view for the future. It underscores the ongoing need for financial support for Brazilian groups actively engaged in experimental research to sustain the Brazilian involvement in the global search for dark matter particles

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arXiv2024

Double-well Inflation: observational constraints and theoretical implications

We revisit the small field double-well inflationary model and investigate its observational viability in light of the current Cosmic Microwave Background data. In particular, considering scenarios with minimal and nonminimal coupling between the inflaton field and the Ricci scalar, we perform a Monte Carlo Markov chain analysis to probe the model's parameter space. We also investigate the consequences of the cosmological results in the canonical type-I seesaw mechanism context and obtain constraints on the vacuum expectation value of the inflaton field, together with the amplitude of the coupling to gravity in the nonminimal case. We employ a Bayesian procedure to compare the model's predictions with the Starobinsky inflationary scenario and find a strong statistical preference for the latter against the minimal and nonminimal coupled double-well scenario.

astro-ph.CO↗
arXiv2024

Is natural inflation in agreement with CMB data?

Natural inflation is a well-motivated model for the early universe in which an inflaton potential of the pseudo-Nambu-Goldstone form, $V(ϕ) = Λ^4[1 + \cos{(ϕ/f)}]$, can naturally drive a cosmic accelerated epoch. This paper investigates the observational viability of the minimally and non-minimally coupled natural inflation scenarios in light of current Cosmic Microwave Background (CMB) observations. We find that a small and negative coupling of the field with gravity can alleviate the well-known observational discrepancies of the minimally coupled model. We perform a Monte Carlo Markov Chain analysis of the Planck 2018 CMB and BICEP/Keck Array B-mode polarization data to estimate how strong the coupling $ξ$ should be to achieve concordance with data. We also briefly discuss the impact of these results on the physical interpretation of the natural inflation scenario.

astro-ph.CO↗
arXiv2021

Discrepancy between cosmological and electroweak observables in Higgs Inflation

In this work, we revisit the non-minimally coupled Higgs Inflation scenario and investigate its observational viability in light of the current Cosmic Microwave Background, Baryon Acoustic Oscillation and type Ia Supernovae data. We explore the effects of the Coleman-Weinberg approximation to the Higgs potential in the primordial universe, connecting the predictions for the Lagrangian parameters at inflationary scales to the electroweak observables through Renormalization Group methods at two-loop order. As the main result, we find that observations on the electroweak scale are in disagreement with the constraints obtained from the cosmological data sets used in the analysis. Specifically, an $\approx 8σ$-discrepancy between the inflationary parameters and the electroweak value of the top quark mass is found, which suggests that a significant deviation from the scenario analysed is required by the cosmological data.

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arXiv2021

Observational constraints on $α$-attractor inflationary models with a Higgs-like potential

We investigate the observational viability of a class of $α$-attractors inflationary models in light of the most recent Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) data. By considering a double-well potential we perform a slow-roll analysis to study the behavior of this class of models, which is a continuous interpolation between the chaotic inflation for large values of $α$ and the universal attractor, i.e., $n_s=1- 2/N$ and $r=α12/N^2$ for small $α$, where $n_s$ is the scalar spectral index, $r$ is the tensor-to-scalar ratio, and $N$ is the e-fold number. In order to explore the parameter space of the model, we also perform a MCMC analysis and find $α=7.56\pm 5.15$ ($1σ$).

astro-ph.CO↗
arXiv2020

Probing the Seesaw Mechanism with Cosmological Data

We investigate cosmological consequences of an inflationary model which incorporates a generic seesaw extension (types I and II) of the Standard Model of Particle Physics. A non-minimal coupling between the inflaton field and the Ricci scalar is considered as well as radiative corrections at one loop order. This connection between the inflationary dynamics with neutrino physics results in a predictive model whose observational viability is investigated in light of the current cosmic microwave background data, baryon acoustic oscillation observations and type Ia supernovae measurements. Our results show that the non-minimal coupled seesaw potential provides a good description of the observational data when radiative corrections are positive. Such result favours the type II seesaw mechanism over type I and may be an indication for physics beyond the Standard Model.

astro-ph.CO↗
arXiv2019

Brazilian Community Report on Dark Matter

This white paper summarizes the activities of the Brazilian community concerning dark matter physics and highlights the importance of financial support to Brazilian groups that are deeply involved in experimental endeavours. The flagships of the Brazilian dark matter program are the Cherenkov Telescope Array, DARKSIDE, SBN and LHC experiments, but we emphasize that smaller experiments such as DAMIC and CONNIE constitute important probes to dark sectors as well and should receive special attention. Small experimental projects showing the potential to probe new regions of parameter space of dark matter models are encouraged. On the theoretical and phenomenological side, some groups are devoted to astrophysical aspects such as the dark matter density profile while others explore the signature of dark matter models at colliders, direct and indirect detection experiments. In summary, the Brazilian dark matter community that was born not long ago has grown tremendously in the past years and now plays an important role in the hunt for a dark matter particle.

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arXiv2017

Inflation scenario driven by a low energy physics inflaton

It is a longstanding desire of cosmologists, and particle physicists as well, to connect inflation to low energy physics, culminating, for instance, in what is known as Higgs inflation. The condition for the standard Higgs boson playing the role of the inflaton, and driving successfully inflation, is that it couples nonminimally with gravity. Nevertheless, cosmological constraints impose that the nonminimal coupling be large. This causes the loss of perturbative unitarity in a scale of energy far below the Planck one. Our aim in this work is to point out that inflaton potential containing a particular type of trilinear coupling involving the inflaton may circumvent this problem by realizing Higgs inflation with tiny nonminimal coupling of the inflaton with gravity. We then develop the idea within a toy model and implement it in the inverse type-II seesaw mechanism for small neutrinos masses.

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arXiv2016

Embedding cosmological inflation, axion dark matter and seesaw mechanism in a 3-3-1 gauge model

The Peccei-Quinn symmetry is an automatic symmetry of the 3-3-1 gauge models which, consequently are not plagued with the strong CP problem. Nevertheless, the axion that emerges from spontaneous breaking of Peccei-Quinn symmetry cannot be made invisible in the original versions of these models, unless we extend their scalar sector by an additional neutral scalar singlet. In this case we show that if, we also add heavy neutrinos in the singlet form, we get to solve three interesting open questions at once: the real component of the neutral scalar singlet driving inflation, the axion playing the role of the dark matter of the universe and standard neutrinos gaining masses through seesaw mechanism.

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arXiv2016

Realizing the supersymmetric inverse seesaw model in the framework of R-parity violation

If, on one hand, the inverse seesaw is the paradigm of TeV scale seesaw mechanism, on the other it is a challenge to find scenarios capable of realizing it. In this work we propose a scenario, based on the framework of R-parity violation, that realizes minimally the supersymmetric inverse seesaw mechanism. In it the energy scale parameters involved in the mechanism are recognized as the vacuum expectation values of the scalars that compose the singlet superfields $\hat N^C$ and $\hat S$. We develop also the scalar sector of the model and show that the Higgs mass receives a new tree-level contribution that, when combined with the standard contribution plus loop correction, is capable of attaining $125$GeV without resort to heavy stops.

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