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Author |
Archidiacono, M.; Giusarma, E.; Hannestad, S.; Mena, O. |
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Title |
Cosmic Dark Radiation and Neutrinos |
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Journal Article |
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Year |
2013 |
Publication |
Advances in High Energy Physics |
Abbreviated Journal |
Adv. High. Energy Phys. |
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Volume |
2013 |
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Pages |
191047 - 14pp |
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Abstract |
New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our cosmological model which is testable by Planck and other observational probes. At the moment, the possible existence of dark radiation is an unsolved question. For instance, the discrepancy between the value of the Hubble constant, H-0, inferred from the Planck data and local measurements of H-0 can to some extent be alleviated by enlarging the minimal ACDM model to include additional relativistic degrees of freedom. From a fundamental physics point of view, dark radiation is no less interesting. Indeed, it could well be one of the most accessible windows to physics beyond the standard model, for example, sterile neutrinos. Here, we review the most recent cosmological results including a complete investigation of the dark radiation sector in order to provide an overview of models that are still compatible with new cosmological observations. Furthermore, we update the cosmological constraints on neutrino physics and dark radiation properties focusing on tensions between data sets and degeneracies among parameters that can degrade our information or mimic the existence of extra species. |
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[Archidiacono, Maria; Hannestad, Steen] Univ Aarhus, Dept Phys & Astron, DK-8000 Aarhus C, Denmark, Email: archi@phys.au.dk |
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Hindawi Publishing Corporation |
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English |
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1687-7357 |
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WOS:000327959400001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1660 |
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Author |
Adey, D. et al; Cervera-Villanueva, A.; Donini, A.; Ghosh, T.; Gomez-Cadenas, J.J.; Hernandez, P.; Izmaylov, A.; Laing, A.; Mena, O.; Sorel, M.; Stamoulis, P. |
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Title |
Light sterile neutrino sensitivity at the nuSTORM facility |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
89 |
Issue |
7 |
Pages |
071301 - 7pp |
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Abstract |
A facility that can deliver beams of electron and muon neutrinos from the decay of a stored muon beam has the potential to unambiguously resolve the issue of the evidence for light sterile neutrinos that arises in short-baseline neutrino oscillation experiments and from estimates of the effective number of neutrino flavors from fits to cosmological data. In this paper, we show that the nuSTORM facility, with stored muons of 3.8 GeV/c +/- 10%, will be able to carry out a conclusive muon neutrino appearance search for sterile neutrinos and test the LSND and MiniBooNE experimental signals with 10 sigma sensitivity, even assuming conservative estimates for the systematic uncertainties. This experiment would add greatly to our knowledge of the contribution of light sterile neutrinos to the number of effective neutrino flavors from the abundance of primordial helium production and from constraints on neutrino energy density from the cosmic microwave background. The appearance search is complemented by a simultaneous muon neutrino disappearance analysis that will facilitate tests of various sterile neutrino models. |
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[Adey, D.; Brice, S. J.; Bross, A. D.; Cease, H.; Geelhoed, M.; Kobilarcik, T.; Liu, A.; Mokhov, N.; Morfin, J.; Neuffer, D.; Palmer, M. A.; Parke, S.; Plunkett, R.; Popovic, M.; Rubinov, P.; Sen, T.; Snopok, P.; Striganov, S.] Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA, Email: Ryan.Bayes@glasgow.ac.uk |
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Amer Physical Soc |
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English |
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1550-7998 |
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Notes |
WOS:000334317200002 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1753 |
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Author |
Di Valentino, E.; Giusarma, E.; Lattanzi, M.; Melchiorri, A.; Mena, O. |
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Title |
Axion cold dark matter: Status after Planck and BICEP2 |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
4 |
Pages |
043534 - 11pp |
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Abstract |
We investigate the axion dark matter scenario (ADM), in which axions account for all of the dark matter in the Universe, in light of the most recent cosmological data. In particular, we use the Planck temperature data, complemented by WMAP E-polarization measurements, as well as the recent BICEP2 observations of B-modes. Baryon acoustic oscillation data, including those from the baryon oscillation spectroscopic survey, are also considered in the numerical analyses. We find that, in the minimal ADM scenario and for Delta(QCD) = 200 MeV, the full data set implies that the axion mass m(a) = 82.2 +/- 1.1 μeV [corresponding to the Peccei-Quinn symmetry being broken at a scale f(a) = (7.54 +/- 0.10) x 10(10) GeV], or m(a) = 76.6 +/- 2.6 μeV [f(a) = (8.08 +/- 0.27) x 10(10) GeV] when we allow for a nonstandard effective number of relativistic species N-eff. We also find a 2 sigma preference for N-eff > 3.046. The limit on the sum of neutrino masses is Sigma m(v) < 0.25 eV at 95% C.L. for N-eff = 3.046, or Sigma m(v) < 0.47 eV when N-eff is a free parameter. Considering extended scenarios where either the dark energy equation-of-state parameter w, the tensor spectral index n(t), or the running of the scalar index dn(s)/d ln k is allowed to vary does not change significantly the axion mass-energy density constraints. However, in the case of the full data set exploited here, there is a preference for a nonzero tensor index or scalar running, driven by the different tensor amplitudes implied by the Planck and BICEP2 observations. We also study the effect on our estimates of theoretical uncertainties, in particular the imprecise knowledge of the QCD scale Delta(QCD), in the calculation of the temperature-dependent axion mass. We find that in the simplest ADM scenario the Planck + WP data set implies that the axion mass m(a) = 63.7 +/- 1.2 μeV for Delta(QCD) = 400 MeV. We also comment on the possibility that axions do not make up for all the dark matter, or that the contribution of string-produced axions has been grossly underestimated; in that case, the values that we find for the mass can conservatively be considered as lower limits. Dark matter axions with mass in the 60-80 μeV (corresponding to an axion-photon coupling G(a gamma gamma) similar to 10(-14) GeV-1) range can, in principle, be detected by looking for axion-to-photon conversion occurring inside a tunable microwave cavity permeated by a high-intensity magnetic field, and operating at a frequency nu similar or equal to 15-20 GHz. This is out of the reach of current experiments like the axion dark matter experiment (limited to a maximum frequency of a few GHzs), but is, on the other hand, within the reach of the upcoming axion dark matter experiment-high frequency experiment that will explore the 4-40 GHz frequency range and then be sensitive to axion masses up to similar to 160 μeV. |
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[Di Valentino, Eleonora; Giusarma, Elena; Melchiorri, Alessandro] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy |
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Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Conference |
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Notes |
WOS:000340890100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1893 |
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Author |
Mena, O.; Palomares-Ruiz, S.; Vincent, A.C. |
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Title |
Flavor Composition of the High-Energy Neutrino Events in IceCube |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
113 |
Issue |
9 |
Pages |
091103 - 5pp |
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Abstract |
The IceCube experiment has recently reported the observation of 28 high-energy (> 30 TeV) neutrino events, separated into 21 showers and 7 muon tracks, consistent with an extraterrestrial origin. In this Letter, we compute the compatibility of such an observation with possible combinations of neutrino flavors with relative proportion (alpha(e:)alpha(mu):alpha tau)(circle plus). Although the 7: 21 track-to-shower ratio is naively favored for the canonical (1:1:1)(circle plus) at Earth, this is not true once the atmospheric muon and neutrino backgrounds are properly accounted for. We find that, for an astrophysical neutrino E-2 energy spectrum, (1:1:1)(circle plus). at Earth is disfavored at 81% C. L. If this proportion does not change, 6 more years of data would be needed to exclude (1:1:1)(circle plus) at Earth at 3 sigma C.L. Indeed, with the recently released 3-yr data, that flavor composition is excluded at 92% C. L. The best fit is obtained for (1:0:0)(circle plus). at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. If confirmed, this result would suggest either a misunderstanding of the expected background events or a misidentification of tracks as showers, or even more compellingly, some exotic physics which deviates from the standard scenario. |
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[Mena, Olga; Palomares-Ruiz, Sergio; Vincent, Aaron C.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain, Email: omena@ific.uv.es; |
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Amer Physical Soc |
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English |
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0031-9007 |
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Notes |
WOS:000341292800005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1920 |
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Author |
Barranco, L.; Boubekeur, L.; Mena, O. |
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Title |
Model-independent fit to Planck and BICEP2 data |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
6 |
Pages |
063007 - 7pp |
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Abstract |
Inflation is the leading theory to describe elegantly the initial conditions that led to structure formation in our Universe. In this paper, we present a novel phenomenological fit to the Planck, WMAP polarization (WP) and the BICEP2 data sets using an alternative parametrization. Instead of starting from inflationary potentials and computing the inflationary observables, we use a phenomenological parametrization due to Mukhanov, describing inflation by an effective equation of state, in terms of the number of e-folds and two phenomenological parameters alpha and beta. Within such a parametrization, which captures the different inflationary models in a model-independent way, the values of the scalar spectral index n(s), its running and the tensor-to-scalar ratio r are predicted, given a set of parameters (alpha, beta). We perform a Markov Chain Monte Carlo analysis of these parameters, and we show that the combined analysis of Planck and WP data favors the Starobinsky and Higgs inflation scenarios. Assuming that the BICEP2 signal is not entirely due to foregrounds, the addition of this last data set prefers instead the phi(2) chaotic models. The constraint we get from Planck and WP data alone on the derived tensor-to-scalar ratio is r < 0.18 at 95% C.L., value which is consistent with the one quoted from the BICEP2 Collaboration analysis, r = 0.16(-0.05)(+0-06), after foreground subtraction. This is not necessarily at odds with the 2 sigma tension found between Planck and BICEP2 measurements when analyzing data in terms of the usual n(s) and r parameters, given that the parametrization used here, for the preferred value n(s) similar or equal to 0.96, allows only for a restricted parameter space in the usual (n(s), r) plane. |
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Address |
[Barranco, Laura; Boubekeur, Lotfi; Mena, Olga] Univ Valencia, CSIC, Inst Fis Corpuscular, E-46071 Valencia, Spain |
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Amer Physical Soc |
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English |
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1550-7998 |
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Notes |
WOS:000342128700002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1933 |
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Author |
Boubekeur, L.; Giusarma, E.; Mena, O.; Ramirez, H. |
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Title |
Current status of modified gravity |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
10 |
Pages |
103512 - 10pp |
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Keywords |
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Abstract |
We revisit the cosmological viability of the Hu-Sawicki modified gravity scenario. The impact of such a modification on the different cosmological observables, including gravitational waves, is carefully described. The most recent cosmological data, as well as constraints on the relationship between the clustering parameter sigma(8) and the current matter mass-energy density Omega(m) from cluster number counts and weak lensing tomography, are considered in our numerical calculations. The strongest bound we find is vertical bar f(R0)vertical bar < 3.7 x 10(-6) at 95% C.L. Forthcoming cluster surveys covering 10 000 deg(2) in the sky, with galaxy surface densities of O(10) arcmin(-2) could improve the precision in the sigma(8)-Omega(m) relationship, tightening the above constraint. |
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Address |
[Boubekeur, Lotfi; Mena, Olga; Ramirez, Hector] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Notes |
WOS:000345534500005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2017 |
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Author |
Archidiacono, M.; Lopez-Honorez, L.; Mena, O. |
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Title |
Current constraints on early and stressed dark energy models and future 21 cm perspectives |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
12 |
Pages |
123016 - 10pp |
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Keywords |
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Abstract |
Despite the great progress of current cosmological measurements, the nature of the dominant component of the Universe, coined dark energy, is still an open question. Early dark energy is a possible candidate which may also alleviate some fine-tuning issues of the standard paradigm. Using the latest available cosmological data, we find that the 95% C.L. upper bound on the early dark energy density parameter is Tau(eDE) < 0.009. On the other hand, the dark energy component may be a stressed and inhomogeneous fluid. If this is the case, the effective sound speed and the viscosity parameters are unconstrained by current data. Future omniscopelike 21 cm surveys, combined with present cosmic microwave background data, could be able to distinguish between standard quintessence scenarios from other possible models with 2 sigma significance, assuming a non-negligible early dark energy contribution. The precision achieved on the Omega(eDE) parameter from these 21 cm probes could be below O(10%). |
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Address |
[Archidiacono, Maria] Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark |
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Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Conference |
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Notes |
WOS:000347194400007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2066 |
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Author |
Giusarma, E.; Di Valentino, E.; Lattanzi, M.; Melchiorri, A.; Mena, O. |
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Title |
Relic neutrinos, thermal axions, and cosmology in early 2014 |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
4 |
Pages |
043507 - 17pp |
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Keywords |
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Abstract |
We present up-to-date cosmological bounds on the sum of active neutrino masses as well as on extended cosmological scenarios with additional thermal relics, as thermal axions or sterile neutrino species. Our analyses consider all the current available cosmological data in the beginning of year 2014, including the very recent and most precise baryon acoustic oscillation measurements from the Baryon Oscillation Spectroscopic Survey. In the minimal three-active-neutrino scenario, we find Sigma m(nu) < 0.22 eV at 95% C.L. from the combination of cosmic microwave background (CMB), baryon acoustic oscillation, and Hubble Space Telescope measurements of the Hubble constant. A nonzero value for the sum of the three active neutrino masses of similar to 0.3 eV is significantly favored at more than three standard deviations when adding the constraints on s 8 and Om from the Planck cluster catalog on galaxy number counts. This preference for nonzero thermal relic masses disappears almost completely in both the thermal axion and massive sterile neutrino schemes. Extra light species contribute to the effective number of relativistic degrees of freedom, parametrized via N-eff. We found that when the recent detection of B mode polarization from the BICEP2 experiment is considered, an analysis of the combined CMB data in the framework of LCDM + r models gives N-eff = 3.90 +/- 0.42, suggesting the presence of an extra relativistic relic at more than 95% C.L. from CMB-only data. |
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Address |
[Giusarma, Elena; Di Valentino, Eleonora; Melchiorri, Alessandro] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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1550-7998 |
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Notes |
WOS:000347985100004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2075 |
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Author |
Boubekeur, L.; Giusarma, E.; Mena, O.; Ramirez, H. |
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Title |
Phenomenological approaches of inflation and their equivalence |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
91 |
Issue |
8 |
Pages |
083006 - 8pp |
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Keywords |
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Abstract |
In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equivalent from the observational viewpoint, as they single out the same areas in the parameter space, and agree with the inflationary attractors where successful inflation occurs. Rephrased in terms of the familiar picture of a slowly rolling, canonically normalized scalar field, the resulting inflaton excursions in these two approaches are almost identical. Furthermore, once the Galactic dust polarization data from Planck are included in the numerical fits, inflaton excursions can safely take sub-Planckian values. |
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Address |
[Boubekeur, Lotfi; Mena, Olga; Ramirez, Hector] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
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ISSN |
1550-7998 |
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Conference |
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Notes |
WOS:000353138800002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2196 |
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Author |
Boubekeur, L.; Giusarma, E.; Mena, O.; Ramirez, H. |
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Title |
Do current data prefer a nonminimally coupled inflaton? |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
91 |
Issue |
10 |
Pages |
103004 - 6pp |
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Keywords |
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Abstract |
We examine the impact of a nonminimal coupling of the inflaton to the Ricci scalar, 1/2 xi R phi(2), on the inflationary predictions. Such a nonminimal coupling is expected to be present in the inflaton Lagrangian on fairly general grounds. As a case study, we focus on the simplest inflationary model governed by the potential V proportional to phi(2), using the latest combined 2015 analysis of Planck and the BICEP2/Keck Array. We find that the presence of a coupling xi is favored at a significance of 99% C.L., assuming that nature has chosen the potential V proportional to phi(2) to generate the primordial perturbations and a number of e-foldings N = 60. Within the context of the same scenario, we find that the value of xi is different from zero at the 2 sigma level. When considering the cross-correlation polarization spectra from the BICEP2/Keck Array and Planck, a value of r = 0.038(-0.030)(+0.039) is predicted in this particular nonminimally coupled scenario. Future cosmological observations may therefore test these values of r and verify or falsify the nonminimally coupled model explored here. |
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Address |
[Boubekeur, Lotfi; Mena, Olga; Ramirez, Hector] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
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Language |
English |
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ISSN |
1550-7998 |
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Notes |
WOS:000354979300001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
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2237 |
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