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Author |
Figueroa, D.G.; Raatikainen, S.; Rasanen, S.; Tomberg, E. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Implications of stochastic effects for primordial black hole production in ultra-slow-roll inflation |
Type |
Journal Article |
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Year |
2022 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
05 |
Issue |
5 |
Pages |
027 - 48pp |
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Keywords |
inflation; primordial black holes; dark matter theory; massive black holes |
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Abstract |
We study the impact of stochastic noise on the generation of primordial black hole (PBH) seeds in ultra-slow-roll (USR) inflation with numerical simulations. We consider the non-linearity of the system by consistently taking into account the noise dependence on the inflaton perturbations, while evolving the perturbations on the coarse-grained background affected by the noise. We capture in this way the non-Markovian nature of the dynamics, and demonstrate that non-Markovian effects are subleading. Using the Delta N formalism, we find the probability distribution P(R) of the comoving curvature perturbation R. We consider inflationary potentials that fit the CMB and lead to PBH dark matter with i) asteroid, ii) solar, or iii) Planck mass, as well as iv) PBHs that form the seeds of supermassive black holes. We find that stochastic effects enhance the PBH abundance by a factor of O(10)-O(10(8)), depending on the PBH mass. We also show that the usual approximation, where stochastic kicks depend only on the Hubble rate, either underestimates or overestimates the abundance by orders of magnitude, depending on the potential. We evaluate the gauge dependence of the results, discuss the quantum-to-classical transition, and highlight open issues of the application of the stochastic formalism to USR inflation. |
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Address |
[Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, E-46980 Valencia, Spain, Email: daniel.figueoa@ific.uv.es; |
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Publisher |
IOP Publishing Ltd |
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Language |
English |
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ISSN |
1475-7516 |
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Conference |
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Notes |
WOS:000804493000010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5239 |
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Permanent link to this record |
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Author |
Domcke, V.; Ema, Y.; Sandner, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Perturbatively including inhomogeneities in axion inflation |
Type |
Journal Article |
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Year |
2024 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
03 |
Issue |
3 |
Pages |
019 - 24pp |
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Keywords |
axions; inflation; particle physics- cosmology connection |
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Abstract |
Axion inflation, i.e. an axion-like inflaton coupled to an Abelian gauge field through a Chern-Simons interaction, comes with a rich and testable phenomenology. This is particularly true in the strong backreaction regime, where the gauge field production heavily impacts the axion dynamics. Lattice simulations have recently demonstrated the importance of accounting for inhomogeneities of the axion field in this regime. We propose a perturbative scheme to account for these inhomogeneities while maintaining high computational efficiency. Our goal is to accurately capture deviations from the homogeneous axion field approximation within the perturbative regime as well as self -consistently determine the onset of the nonperturbative regime. |
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Address |
[Domcke, Valerie] CERN, Theoret Phys Dept, Geneva 23, Switzerland, Email: valerie.domcke@cern.ch; |
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Publisher |
IOP Publishing Ltd |
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English |
Summary Language |
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Original Title |
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ISSN |
1475-7516 |
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Conference |
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Notes |
WOS:001185016600002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6020 |
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Permanent link to this record |
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Author |
Giare, W.; Renzi, F.; Mena, O.; Di Valentino, E.; Melchiorri, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Is the Harrison-Zel'dovich spectrum coming back? ACT preference for n(s) similar to 1 and its discordance with Planck |
Type |
Journal Article |
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Year |
2023 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
521 |
Issue |
2 |
Pages |
2911-2918 |
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Keywords |
cosmological parameters; inflation; cosmology: observations; cosmology: theory |
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Abstract |
The Data Release 4 of the Atacama Cosmology Telescope (ACT) shows an agreement with an Harrison-Zel'dovich primordial spectrum (n(s) = 1.009 +/- 0.015), introducing a tension with a significance of 99.3 per cent Confidence Level (CL) with the results from the Planck satellite. The discrepancy on the value of the scalar spectral index is neither alleviated with the addition of large scale structure information nor with the low multipole polarization data. We discuss possible avenues to alleviate the tension relying on either neglecting polarization measurements from ACT or in extending different sectors of the theory. |
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Address |
[Giare, William] Ctr Nazl INFN Studi Avanzati, Galileo Galileo Inst Theoret Phys, Largo Enr Fermi 2, I-50125 Florence, Italy, Email: william.giare@gmail.com |
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Publisher |
Oxford Univ Press |
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English |
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ISSN |
0035-8711 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000957248500013 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5510 |
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Permanent link to this record |
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Author |
Gariazzo, S.; Mena, O.; Ramirez, H.; Boubekeur, L. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Primordial power spectrum features in phenomenological descriptions of inflation |
Type |
Journal Article |
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Year |
2017 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
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Volume |
17 |
Issue |
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Pages |
38-45 |
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Keywords |
Inflation; Primordial power spectrum; Sound speed |
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Abstract |
We extend an alternative, phenomenological approach to inflation by means of an equation of state and a sound speed, both of them functions of the number of e-folds and four phenomenological parameters. This approach captures a number of possible inflationary models, including those with non-canonical kinetic terms or scale-dependent non-gaussianities. We perform Markov Chain Monte Carlo analyses using the latest cosmological publicly available measurements, which include Cosmic Microwave Background (CMB) data from the Planck satellite. Within this parameterization, we discard scale invariance with a significance of about 10 sigma, and the running of the spectral index is constrained as alpha(s) = -0.60(-0.10)(+0.08) x 10(-3) (68% CL errors). The limit on the tensor-to-scalar ratio is r < 0.005 at 95% CL from CMB data alone. We find no significant evidence for this alternative parameterization with present cosmological observations. The maximum amplitude of the equilateral non-gaussianity that we obtain, vertical bar f(NL)(equil)vertical bar < 1, is much smaller than the current Planck mission errors, strengthening the case for future high-redshift, all-sky surveys, which could reach the required accuracy on equilateral non-gaussianities. |
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Address |
[Gariazzo, Stefano] Univ Turin, Dept Phys, Via P Giuria 1, I-10125 Turin, Italy, Email: omena@ific.uv.es |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2212-6864 |
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Notes |
WOS:000411869100006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3319 |
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Permanent link to this record |
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Author |
Sanchis-Lozano, M.A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Stringy Signals from Large-Angle Correlations in the Cosmic Microwave Background? |
Type |
Journal Article |
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Year |
2022 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Universe |
Abbreviated Journal |
Universe |
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Volume |
8 |
Issue |
8 |
Pages |
396 - 13pp |
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Keywords |
cosmic microwave background; angular correlations; inflation; string theory |
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Abstract |
We interpret the lack of large-angle temperature correlations and the even-odd parity imbalance observed in the cosmic microwave background (CMB) by COBE, WMAP and Planck satellite missions as a possible stringy signal ultimately stemming from a composite inflaton field (e.g., a fermionic condensate). Based on causality arguments and a Fourier analysis of the angular two-point correlation function, two infrared cutoffs k(min)(even,odd) (satisfying k(min)(even) similar or equal to 2k(min)(odd)) are introduced to the CMB power spectrum associated, respectively, with periodic and antiperiodic boundary conditions of the fermionic constituents (echoing the Neveu-Schwarz-Ramond model in superstring theory), without resorting to any particular model. |
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Address |
[Sanchis-Lozano, Miguel-Angel] Univ Valencia, Dept Theoret Phys, Doctor Moliner 50, Burjassot 46011, Spain, Email: miguel.angel.sanchis@ific.uv.es |
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Publisher |
Mdpi |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Conference |
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Notes |
WOS:000845107300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5344 |
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Permanent link to this record |