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Author |
Capozziello, S.; Harko, T.; Lobo, F.S.N.; Olmo, G.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Hybrid Modified Gravity Unifying Local Tests, Galactic Dynamics and Late-Time Cosmic Acceleration |
Type |
Journal Article |
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Year |
2013 |
Publication |
International Journal of Modern Physics D |
Abbreviated Journal |
Int. J. Mod. Phys. D |
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Volume |
22 |
Issue |
12 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
1342006 - 7pp |
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Keywords |
Modified gravity; late-time cosmic acceleration; dark matter; solar system tests |
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Abstract |
The nonequivalence between the metric and Palatini formalisms of f(R) gravity is an intriguing feature of these theories. However, in the recently proposed hybrid metric-Palatini gravity, consisting of the superposition of the metric Einstein-Hilbert Lagrangian with an f(R) term constructed a la Palatini, the “true” gravitational field is described by the interpolation of these two nonequivalent approaches. The theory predicts the existence of a light long-range scalar field, which passes the local constraints and affects the galactic and cosmological dynamics. Thus, the theory opens new possibilities for a unified approach, in the same theoretical framework, to the problems of dark energy and dark matter, without distinguishing a priori matter and geometric sources, but taking their dynamics into account under the same standard. |
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Address |
[Capozziello, Salvatore] Univ Naples Federico II, Dipartimento Fis, I-80126 Naples, Italy, Email: capozzie@na.infn.it; |
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World Scientific Publ Co Pte Ltd |
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English |
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ISSN |
0218-2718 |
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Notes |
WOS:000329048900013 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1688 |
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Permanent link to this record |
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Author |
Capozziello, S.; Harko, T.; Lobo, F.S.N.; Olmo, G.J.; Vignolo, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The Cauchy problem in hybrid metric-Palatini f(X)-gravity |
Type |
Journal Article |
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Year |
2014 |
Publication |
International Journal of Geometric Methods in Modern Physics |
Abbreviated Journal |
Int. J. Geom. Methods Mod. Phys. |
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Volume |
11 |
Issue |
5 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
1450042 - 12pp |
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Keywords |
Cauchy problem; modified gravity; hybrid metric-Palatini gravity |
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Abstract |
The well-formulation and the well-posedness of the Cauchy problem are discussed for hybrid metric-Palatini gravity, a recently proposed modified gravitational theory consisting of adding to the Einstein-Hilbert Lagrangian an f(R)-term constructed a la Palatini. The theory can be recast as a scalar-tensor one predicting the existence of a light long-range scalar field that evades the local Solar System tests and is able to modify galactic and cosmological dynamics, leading to the late-time cosmic acceleration. In this work, adopting generalized harmonic coordinates, we show that the initial value problem can always be well-formulated and, furthermore, can be well-posed depending on the adopted matter sources. |
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Address |
[Capozziello, Salvatore] Univ Naples Federico II, Dipartimento Sci Fis, Naples, Italy, Email: capozzie@na.infn.it; |
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Publisher |
World Scientific Publ Co Pte Ltd |
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English |
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0219-8878 |
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Notes |
WOS:000336527100003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1813 |
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Permanent link to this record |
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Author |
Olmo, G.J.; Rubiera-Garcia, D. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The quantum, the geon and the crystal |
Type |
Journal Article |
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Year |
2015 |
Publication |
International Journal of Modern Physics D |
Abbreviated Journal |
Int. J. Mod. Phys. D |
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Volume |
24 |
Issue |
9 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
1542013 - 15pp |
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Keywords |
Effective geometries; crystalline structures; modified gravity; metric-affine approach; geons |
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Abstract |
Effective geometries arising from a hypothetical discrete structure of spacetime can play an important role in the understanding of the gravitational physics beyond General Relativity (GR). To discuss this question, we make use of lessons from crystalline systems within solid state physics, where the presence of defects in the discrete microstructure of the crystal determine the kind of effective geometry needed to properly describe the system in the macroscopic continuum limit. In this work, we study metric-affine theories with nonmetricity and torsion, which are the gravitational analog of crystalline structures with point defects and dislocations. We consider a crystal-motivated gravitational action and show the presence of topologically nontrivial structures (wormholes) supported by an electromagnetic field. Their existence has important implications for the quantum foam picture and the effective gravitational geometries. We discuss how the dialogue between solid state physics systems and modified gravitational theories can provide useful insights on both sides. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, CSIC, Fac Fis, Dept Fis Teor, E-46100 Valencia, Spain, Email: drubiera@fudan.edu.cn |
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Publisher |
World Scientific Publ Co Pte Ltd |
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English |
Summary Language |
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Series Editor |
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Series Volume |
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ISSN |
0218-2718 |
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Notes |
WOS:000358793200014 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2322 |
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Permanent link to this record |
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Author |
Sepehri, A.; Pincak, R.; Olmo, G.J. |
![find record details (via OpenURL) openurl](img/xref.gif)
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Title |
M-theory, graphene-branes and superconducting wormholes |
Type |
Journal Article |
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Year |
2017 |
Publication |
International Journal of Geometric Methods in Modern Physics |
Abbreviated Journal |
Int. J. Geom. Methods Mod. Phys. |
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Volume |
14 |
Issue |
11 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
1750167 - 32pp |
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Keywords |
M-theory; wormholes; graphene; superconductors |
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Abstract |
Exploiting an M-brane system whose structure and symmetries are inspired by those of graphene (what we call a graphene-brane), we propose here a similitude between two layers of graphene joined by a nanotube and wormholes scenarios in the brane world. By using the symmetries and mathematical properties of the M-brane system, we show here how to possibly increase its conductivity, to the point of making it as a superconductor. The questions of whether and under which condition this might point to the corresponding real graphene structures becoming superconducting are briefly outlined. |
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Address |
[Sepehri, Alireza] Shahid Bahonar Univ, Fac Phys, POB 76175, Kerman, Iran, Email: alireza.sepehri@uk.ac.ir; |
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Publisher |
World Scientific Publ Co Pte Ltd |
Place of Publication |
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English |
Summary Language |
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Series Editor |
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Series Volume |
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ISSN |
0219-8878 |
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Expedition |
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Conference |
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Notes |
WOS:000413442500018 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3334 |
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Permanent link to this record |
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Author |
Izadi, A.; Shacker, S.S.; Olmo, G.J.; Banerjee, R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Observational effects of varying speed of light in quadratic gravity cosmological models |
Type |
Journal Article |
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Year |
2018 |
Publication |
International Journal of Geometric Methods in Modern Physics |
Abbreviated Journal |
Int. J. Geom. Methods Mod. Phys. |
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Volume |
15 |
Issue |
5 |
Pages ![sorted by First Page field, ascending order (up)](img/sort_asc.gif) |
1850084 - 16pp |
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Keywords |
Palatini formalism; modified gravity; causal structure constant; varying speed of light |
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Abstract |
We study different manifestations of the speed of light in theories of gravity where metric and connection are regarded as independent fields. We find that for a generic gravity theory in a frame with locally vanishing affine connection, the usual degeneracy between different manifestations of the speed of light is broken. In particular, the space-time causal structure constant (c(ST)) may become variable in that local frame. For theories of the form f(R, R-mu nu R-mu nu), this variation in c(ST) has an impact on the definition of the luminosity distance (and distance modulus), which can be used to confront the predictions of particular models against Supernovae type Ia (SN Ia) data. We carry out this test for a quadratic gravity model without cosmological constant assuming (i) a constant speed of light and (ii) a varying speed of light (VSL), and find that the latter scenario is favored by the data. |
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Address |
[Izadi, Azam] Khajeh Nasir Toosi Univ Technol, Dept Phys, Tehran, Iran, Email: aizadi@kntu.ac.ir; |
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Corporate Author |
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Thesis |
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Publisher |
World Scientific Publ Co Pte 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 |
0219-8878 |
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:000429106400016 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3553 |
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Permanent link to this record |