174 citations · 1.3k across the 27 of their papers we have counts for
29 papers
Axion Inflation with a Massive Abelian Gauge Field
Ricardo Z. Ferreira, Alessio Notari, José Jaime Terente Díaz
An axial coupling between an inflaton and an Abelian gauge field can trigger the tachyonic amplification of one gauge-field helicity. For a massless vector, modes with physical mom…
CMB and Lyman- constraints on dark matter decays to photons
Francesco Capozzi, Ricardo Z. Ferreira, Laura Lopez-Honorez +1
Dark matter energy injection in the early universe modifies both the ionization history and the temperature of the intergalactic medium. In this work, we improve the CMB bounds on…
Superradiant axion clouds around asteroid-mass primordial black holes
Nuno P. Branco, Ricardo Z. Ferreira, João G. Rosa
We analyze the dynamics and observational signatures of axion clouds formed via the superradiant instability around primordial black holes, focusing on the mass range $10^{14}-10^{…
Do direct detection experiments constrain axionlike particles coupled to electrons?
Ricardo Z. Ferreira, M. C. David Marsh, Eike Müller
Several laboratory experiments have published limits on axionlike particles (ALPs) with feeble couplings to electrons and masses in the keV-MeV range, under the assumption that suc…
EuCAPT White Paper: Opportunities and Challenges for Theoretical Astroparticle Physics in the Next Decade
R. Alves Batista, M. A. Amin, G. Barenboim +134
Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the…
High Quality QCD Axion at Gravitational Wave Observatories
Ricardo Z. Ferreira, Alessio Notari, Oriol Pujolàs +1
The axion solution to the strong CP problem is delicately sensitive to Peccei-Quinn breaking contributions that are misaligned with respect to QCD instantons. Heavy QCD axion model…
The DFSZ axion in the CMB
Ricardo Z. Ferreira, Alessio Notari, Fabrizio Rompineve
We perform for the first time a dedicated analysis of cosmological constraints on DFSZ QCD axion models. Such constructions are especially interesting in light of the recent Xenon-…
Production of Thermal Axions across the ElectroWeak Phase Transition
Fernando Arias-Aragon, Francesco D'Eramo, Ricardo Z. Ferreira +2
Light axions can potentially leave a cosmic background, just like neutrinos. We complete the study of thermal axion production across the electroweak scale by providing a smooth an…
Super-Hawking Radiation
Ricardo Z. Ferreira, Carlo Heissenberg
We discuss modifications to the Hawking spectrum that arise when the asymptotic states are supertranslated or superrotated. For supertranslations we find nontrivial off-diagonal ph…
Cosmic Imprints of XENON1T Axions
Fernando Arias-Aragon, Francesco D'Eramo, Ricardo Z. Ferreira +2
The recent electron recoil excess observed by XENON1T has a possible interpretation in terms of solar axions coupled to electrons. If such axions are still relativistic at recombin…
Non-Gaussianities in models of inflation with large and negative entropic masses
Ricardo Z. Ferreira
Models of inflation where the entropic directions have large and negative masses can be well described by a single-field EFT with an imaginary sound speed . Amon…
Late time transitions in the quintessence field and the tension
Eleonora Di Valentino, Ricardo Z. Ferreira, Luca Visinelli +1
We consider a quintessence field which transitions from a matter-like to a cosmological constant behavior between recombination and the present time. We aim at easing the tension i…
Hot Axions and the tension
Francesco D'Eramo, Ricardo Z. Ferreira, Alessio Notari +1
Scattering and decay processes of thermal bath particles involving heavy leptons can dump hot axions in the primordial plasma around the QCD phase transition. We compute their reli…
Natural Inflation with a periodic non-minimal coupling
Ricardo Z. Ferreira, Alessio Notari, Guillem Simeon
Natural inflation is an attractive model for primordial inflation, since the potential for the inflaton is of the pseudo Nambu-Goldstone form, , and so is…
Observable windows for the QCD axion through
Ricardo Z. Ferreira, Alessio Notari
We show that when the QCD axion is directly coupled to quarks with , such as in DFSZ models, the dominant production mechanism in the earl…
Thermalized axion inflation: natural and monomial inflation with small
Ricardo Z. Ferreira, Alessio Notari
A safe way to reheat the universe, in models of natural and quadratic inflation, is through shift symmetric couplings between the inflaton and the Standard Model (SM), since th…
Thermalized Axion Inflation
Ricardo Z. Ferreira, Alessio Notari
We analyze the dynamics of inflationary models with a coupling of the inflaton to gauge fields of the form , as in the case of axions. It is known that this lea…
Is Patience a Virtue? Cosmic Censorship of Infrared Effects in de Sitter
Ricardo Z. Ferreira, McCullen Sandora, Martin S. Sloth
While the accumulation of long wavelength modes during inflation wreaks havoc on the large scale structure of spacetime, the question of even observability of their presence by any…
Patient Observers and Non-perturbative Infrared Dynamics in Inflation
Ricardo Z. Ferreira, McCullen Sandora, Martin S. Sloth
We have previously derived the effect of soft graviton modes on the quantum state of de Sitter using spontaneously broken asymptotic symmetries. In the present paper we reinterpret…
Asymptotic Symmetries in de Sitter and Inflationary Spacetimes
Ricardo Z. Ferreira, McCullen Sandora, Martin S. Sloth
Soft gravitons produced by the expansion of de Sitter can be viewed as the Nambu-Goldstone bosons of spontaneously broken asymptotic symmetries of the de Sitter spacetime. We expli…
Peculiarities of electron energy spectrum in Coulomb field of super heavy nucleus
D. M. Gitman, B. L. Voronov, R. Ferreira +1
Just after the Dirac equation was established, a number of physicists tried to comment on and solve the spectral problem for the Dirac Hamiltonian with the Coulomb field of arbitra…
The fate of a Universe driven by a linear potential
Ricardo Z. Ferreira, Pedro P. Avelino
We study the proposal to solve the coincidence problem in the non-local version of the vacuum energy sequestering mechanism by means of a scalar field in a linear potential. We sho…
Inflationary dynamics of kinetically-coupled gauge fields
Ricardo Z. Ferreira, Jonathan Ganc
We investigate the inflationary dynamics of two kinetically-coupled massless gauge fields with time-varying kinetic-term coefficients. Ensuring that the system does not have…
Universal Constraints on Axions from Inflation
Ricardo Z. Ferreira, Martin S. Sloth
We consider the presence of an axion like particle, , with a generic violating axial coupling of the form , where is the gauge field streng…