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Author |
Olmo, G.J.; Rubiera-Garcia, D. |
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Title |
Brane-world and loop cosmology from a gravity-matter coupling perspective |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
740 |
Issue |
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Pages |
73-79 |
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Keywords  |
Modified gravity; Palatini formalism; f(R) theories; Gravity-matter coupling; Quadratic cosmology |
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Abstract |
We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an f (R) gravity action plus a g(R) term non-minimally coupled with the matter Lagrangian. The reconstruction algorithm that we provide depends on a free function of the matter density that must be specified in each case and allows to obtain analytical solutions always. In the simplest cases, the function f (R) is quadratic in the Ricci scalar, R, whereas g(R) is linear. Our approach is compared with recent results in the literature. We show that working in the Palatini formalism there is no need to impose any constraint that keeps the equations second order, which is a key requirement for the successful implementation of the reconstruction algorithm. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, CSIC, Ctr Mixto, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.es; |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
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Original Title |
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Series Title |
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Series Volume |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000347046200013 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2099 |
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Author |
Norena, J.; Verde, L.; Jimenez, R.; Pena-Garay, C.; Gomez, C. |
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Title |
Cancelling out systematic uncertainties |
Type |
Journal Article |
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Year |
2012 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
419 |
Issue |
2 |
Pages |
1040-1050 |
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Keywords |
methods: statistical; cosmology: theory |
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Abstract |
We present a method to minimize, or even cancel out, the nuisance parameters affecting a measurement. Our approach is general and can be applied to any experiment or observation where systematic errors are a concern e.g. are larger than statistical errors. We compare it with the Bayesian technique used to deal with nuisance parameters: marginalization, and show how the method compares and improves by avoiding biases. We illustrate the method with several examples taken from the astrophysics and cosmology world: baryonic acoustic oscillations (BAOs), cosmic clocks, Type Ia supernova (SNIa) luminosity distance, neutrino oscillations and dark matter detection. By applying the method we not only recover some known results but also find some interesting new ones. For BAO experiments we show how to combine radial and angular BAO measurements in order to completely eliminate the dependence on the sound horizon at radiation drag. In the case of exploiting SNIa as standard candles we show how the uncertainty in the luminosity distance by a second parameter modelled as a metallicity dependence can be eliminated or greatly reduced. When using cosmic clocks to measure the expansion rate of the universe, we demonstrate how a particular combination of observables nearly removes the metallicity dependence of the galaxy on determining differential ages, thus removing the agemetallicity degeneracy in stellar populations. We hope that these findings will be useful in future surveys to obtain robust constraints on the dark energy equation of state. |
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Address |
[Norena, Jorge; Verde, Licia; Jimenez, Raul] Univ Barcelona IEEC UB, ICREA, Barcelona 08028, Spain, Email: jorge.norena@icc.ub.edu |
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Publisher |
Wiley-Blackwell |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Edition |
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ISSN |
0035-8711 |
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Conference |
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Notes |
WOS:000298482300011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
890 |
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Author |
Semikoz, V.B.; Sokoloff, D.D.; Valle, J.W.F. |
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Title |
Lepton asymmetries and primordial hypermagnetic helicity evolution |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
06 |
Issue |
6 |
Pages |
008 - 12pp |
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Keywords |
Magnetohydrodynamics; galactic magnetic fields; cosmic magnetic fields theory; particle physics – cosmology connection |
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Abstract |
The hypermagnetic helicity density at the electroweak phase transition (EWPT) exceeds many orders of magnitude the galactic magnetic helicity density. Together with previous magnetic helicity evolution calculations after the EWPT and hypermagnetic helicity conversion to the magnetic one at the EWPT, the present calculation completes the description of the evolution of this important topological feature of cosmological magnetic fields. It suggests that if the magnetic field seeding the galactic dynamo has a primordial origin, it should be substantially helical. This should be taken into account in scenarios of galactic magnetic field evolution with a cosmological seed. |
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Address |
[Semikoz, V. B.; Valle, J. W. F.] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, E-46071 Valencia, Spain, Email: semikoz@ific.uv.es; |
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Corporate Author |
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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:000306003500008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1101 |
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Author |
Aristizabal Sierra, D.; Tortola, M.; Valle, J.W.F.; Vicente, A. |
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Title |
Leptogenesis with a dynamical seesaw scale |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
052 - 20pp |
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Keywords |
leptogenesis; baryon asymmetry; particle physics – cosmology connection; neutrino theory |
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Abstract |
In the simplest type-I seesaw leptogenesis scenario right-handed neutrino annihilation processes are absent. However, in the presence of new interactions these processes are possible and can affect the resulting B – L asymmetry in an important way. A prominent example is provided by models with spontaneous lepton number violation, where the existence of new dynamical degrees of freedom can play a crucial role. In this context, we provide a model-independent discussion of the effects of right-handed neutrino annihilations. We show that in the weak washout regime, as long as the scattering processes remain slow compared with the Hubble expansion rate throughout the relevant temperature range, the efficiency can be largely enhanced, reaching in some cases maximal values. Moreover, the B – L asymmetry yield turns out to be independent upon initial conditions, in contrast to the “standard” case. On the other hand, when the annihilation processes are fast, the right-handed neutrino distribution tends to a thermal one down to low temperatures, implying a drastic suppression of the efficiency which in some cases can render the B – L generation mechanism inoperative. |
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Address |
[Sierra, D. Aristizabal; Vicente, A.] Univ Liege, IFPA, Dept Astrophys Geophys & Oceanog, B-4000 Liege, Belgium, Email: daristizabal@ulg.ac.be; |
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Corporate Author |
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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:000339802700053 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1868 |
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Author |
LISA Cosmology Working Group (Auclair, P. et al); Figueroa, D.G. |
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Title |
Cosmology with the Laser Interferometer Space Antenna |
Type |
Journal Article |
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Year |
2023 |
Publication |
Living Reviews in Relativity |
Abbreviated Journal |
Living Rev. Relativ. |
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Volume |
26 |
Issue |
1 |
Pages |
5 - 254pp |
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Keywords |
Laser Interferometer Space Antenna (LISA); Cosmology |
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Abstract |
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by LISA to probe the universe. |
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Address |
[Auclair, Pierre; Caprini, Chiara; Mangiagli, Alberto; Papanikolaou, Theodoros; Pol, Alberto Roper; Steer, Daniele A.; Vennin, Vincent; Petiteau, Antoine] Univ Paris, CNRS, Lab Astroparticule & Cosmol, F-75013 Paris, France, Email: chairscoswg@gmail.com |
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Corporate Author |
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Thesis |
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Publisher |
Springer Int Publ Ag |
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 |
2367-3613 |
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:001063967800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5755 |
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