| Records |
| Author |
Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J.; Ringeval, C. |
| Title |
Cascading dust inflation in Born-lnfeld gravity |
Type |
Journal Article |
| Year |
2015 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
| Volume |
11 |
Issue  |
11 |
Pages |
046 - 30pp |
| Keywords |
modified gravity; inflation |
| Abstract |
In the framework of Born-Infeld inspired gravity theories, which deviates from General Relativity (GR) in the high curvature regime, we discuss the viability of Cosmic Inflation without scalar fields. For energy densities higher than the new mass scale of the theory, a gravitating (lust component is shown to generically induce an accelerated expansion of the Universe. Within such a simple scenario, inflation gracefiffly exits when the CR regime is recovered, but the Universe would remain matter dominated. In order to implement a reheating era after inflation, we then consider inflation to be driven by a mixture of unstable dust species decaying into radiation. Because the speed of sound gravitates within the BornInfeld model under consideration, our scenario ends up being predictive on various open questions of the inflationary paradigm. The total number of e-folds of acceleration is given by the lifetime of the unstable dust components and is related to the duration of reheating. As a result, inflation does not last much longer than the number of e-folds of deceleration allowing a small spatial curvature and large scale deviations to isotropy to be observable today. Energy densities are self-regulated as inflation can only start for a total energy density less than a threshold value, again related to the species' lifetime. Above this threshold, the Universe may bc nee thereby avoiding a singularity. Another distinctive feature is that the accelerated expansion is of the superinflationary ldnd, namely the first Hubble flow function is negative. We show however that the tensor modes are never excited and the tensor-to-scalar ratio is always vanishing, independently of the energy scale of inflation. |
| Address |
[Jimenez, Jose Beltran] Aix Marseille Univ, Ctr Phys Theor, UMR 7332, F-13288 Marseille, France, Email: jose.beltran@cpt.univ-mrs.fr; |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
Place of Publication |
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| Language |
English |
Summary Language |
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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 |
1475-7516 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000365821200047 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
2478 |
| Permanent link to this record |
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| Author |
Pallis, C. |
| Title |
Reconciling induced-gravity inflation in supergravity with the Planck 2013 & BICEP2 results |
Type |
Journal Article |
| Year |
2014 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
| Volume |
10 |
Issue |
10 |
Pages |
058 - 18pp |
| Keywords |
supersymmetry and cosmology; inflation; modified gravity |
| Abstract |
We generalize the embedding of induced-gravity inflation beyond the no-scale Supergravity presented in ref. [1] employing two gauge singlet chiral superfields, a superpotential uniquely determined by applying a continuous R and a discrete Z(n) symmetries, and a logarithmic Kahler potential including all the allowed terms up to fourth order in powers of the various fields. We show that, increasing slightly the prefactor (-3) encountered in the adopted Kahler potential, an efficient enhancement of the resulting tensor-to-scalar ratio can be achieved rendering the predictions of the model consistent with the recent BICEP2 results, even with subplanckian excursions of the original inflaton field. The remaining inflationary observables can become compatible with the data by mildly tuning the coefficient involved in the fourth order term of the Kahler potential which mixes the inflaton with the accompanying non-inflaton field. The inflaton mass is predicted to be close to 10(14) GeV. |
| Address |
[Pallis, C.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: kpallis@auth.gr |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
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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| 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 |
1475-7516 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000345990800059 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
no |
| Call Number |
IFIC @ pastor @ |
Serial |
2043 |
| Permanent link to this record |
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| Author |
Beltran Jimenez, J.; Heisenberg, L.; Olmo, G.J.; Rubiera-Garcia, D. |
| Title |
On gravitational waves in Born-Infeld inspired non-singular cosmologies |
Type |
Journal Article |
| Year |
2017 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
| Volume |
10 |
Issue |
10 |
Pages |
029 - 23pp |
| Keywords |
alternatives to inflation; modified gravity; physics of the early universe; primordial gravitational waves (theory) |
| Abstract |
We study the evolution of gravitational waves for non-singular cosmological solutions within the framework of Born-Infeld inspired gravity theories, with special emphasis on the Eddington-inspired Born-Infeld theory. We review the existence of two types of non-singular cosmologies, namely bouncing and asymptotically Minkowski solutions, from a perspective that makes their features more apparent. We study in detail the propagation of gravitational waves near these non-singular solutions and carefully discuss the origin and severity of the instabilities and strong coupling problems that appear. We also investigate the role of the adiabatic sound speed of the matter sector in the regularisation of the gravitational waves evolution. We extend our analysis to more general Born-Infeld inspired theories where analogous solutions are found. As a general conclusion, we obtain that the bouncing solutions are generally more prone to instabilities, while the asymptotically Minkowski solutions can be rendered stable, making them appealing models for the early universe. |
| Address |
[Beltran Jimenez, Jose] Univ Toulon & Var, Aix Marseille Univ, CNRS, CPT, Marseille, France, Email: jose.beltran@uam.es; |
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Thesis |
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| Publisher |
Iop Publishing Ltd |
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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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 |
1475-7516 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000413332400002 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
3337 |
| Permanent link to this record |
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| Author |
Gariazzo, S.; Mena, O.; Ramirez, H.; Boubekeur, L. |
| Title |
Primordial power spectrum features in phenomenological descriptions of inflation |
Type |
Journal Article |
| Year |
2017 |
Publication |
Physics of the Dark Universe |
Abbreviated Journal |
Phys. Dark Universe |
| Volume |
17 |
Issue |
|
Pages |
38-45 |
| Keywords |
Inflation; Primordial power spectrum; Sound speed |
| 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. |
| Address |
[Gariazzo, Stefano] Univ Turin, Dept Phys, Via P Giuria 1, I-10125 Turin, Italy, Email: omena@ific.uv.es |
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Thesis |
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| Publisher |
Elsevier Science Bv |
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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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 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000411869100006 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
3319 |
| Permanent link to this record |
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| Author |
Sanchis-Lozano, M.A.; Melia, F.; Lopez-Corredoira, M.; Sanchis-Gual, N. |
| Title |
Missing large-angle correlations versus even-odd point-parity imbalance in the cosmic microwave background |
Type |
Journal Article |
| Year |
2022 |
Publication |
Astronomy & Astrophysics |
Abbreviated Journal |
Astron. Astrophys. |
| Volume |
660 |
Issue |
|
Pages |
A121 - 10pp |
| Keywords |
cosmological parameters; cosmic background radiation; cosmology: observations; cosmology: theory; inflation; large-scale structure of Universe |
| Abstract |
Context. The existence of a maximum correlation angle (theta(max) & 60 greater than or similar to degrees) in the two-point angular temperature correlations of cosmic microwave background (CMB) radiation, measured by WMAP and Planck, stands in sharp contrast to the prediction of standard inflationary cosmology, in which the correlations should extend across the full sky (i.e., 180 degrees). The introduction of a hard lower cuto ff (k(min)) in the primordial power spectrum, however, leads naturally to the existence of theta(max). Among other cosmological anomalies detected in these data, an apparent dominance of odd-over-even parity multipoles has been seen in the angular power spectrum of the CMB. This feature, however, may simply be due to observational contamination in certain regions of the sky. Aims. In attempting to provide a more detailed assessment of whether this odd-over-even asymmetry is intrinsic to the CMB, we therefore proceed in this paper, first, to examine whether this odd-even parity imbalance also manifests itself in the angular correlation function and, second, to examine in detail the interplay between the presence of theta(max) and this observed anomaly. Methods. We employed several parity statistics and recalculated the angular correlation function for di fferent values of the cuto ff kmin in order to optimize the fit to the di fferent Planck 2018 data. Results. We find a phenomenological connection between these features in the data, concluding that both must be considered together in order to optimize the theoretical fit to the Planck 2018 data. Conclusions. This outcome is independent of whether the parity imbalance is intrinsic to the CMB, but if it is, the odd-over-even asymmetry would clearly point to the emergence of new physics. |
| Address |
[Sanchis-Lozano, M-A] Ctr Mixto Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, Dr Moliner 50, Burjassot, Spain, Email: Miguel.Angel.Sanchis@ific.uv.es; |
| Corporate Author |
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Thesis |
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| Publisher |
Edp Sciences S A |
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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| 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 |
0004-6361 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000786712000002 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5211 |
| Permanent link to this record |
