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Author |
Capozziello, S.; Harko, T.; Koivisto, T.S.; Lobo, F.S.N.; Olmo, G.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Wormholes supported by hybrid metric-Palatini gravity |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
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Volume |
86 |
Issue |
12 |
Pages |
127504 - 5pp |
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Abstract |
Recently, a modified theory of gravity was presented, which consists of the superposition of the metric Einstein-Hilbert Lagrangian with an f(R) term constructed a la Palatini. The theory possesses extremely interesting features such as predicting the existence of a long-range scalar field, that explains the late-time cosmic acceleration and passes the local tests, even in the presence of a light scalar field. In this brief report, we consider the possibility that wormholes are supported by this hybrid metric-Palatini gravitational theory. We present here the general conditions for wormhole solutions according to the null energy conditions at the throat and find specific examples. In the first solution, we specify the redshift function, the scalar field and choose the potential that simplifies the modified Klein-Gordon equation. This solution is not asymptotically flat and needs to be matched to a vacuum solution. In the second example, by adequately specifying the metric functions and choosing the scalar field, we find an asymptotically flat spacetime. |
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Address |
[Capozziello, Salvatore] Univ Naples Federico II, Dipartimento Sci Fis, I-80126 Naples, Italy, Email: capozzie@na.infn.it; |
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Amer Physical Soc |
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English |
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1550-7998 |
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Notes |
WOS:000312446600010 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1280 |
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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 |
Importance of torsion and invariant volumes in Palatini theories of gravity |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
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Volume |
88 |
Issue |
8 |
Pages |
084030 - 11pp |
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Abstract |
We study the field equations of extensions of general relativity formulated within a metric-affine formalism setting torsion to zero (Palatini approach). We find that different (second-order) dynamical equations arise depending on whether torsion is set to zero (i) a priori or (ii) a posteriori, i.e., before or after considering variations of the action. Considering a generic family of Ricci-squared theories, we show that in both cases the connection can be decomposed as the sum of a Levi-Civita connection and terms depending on a vector field. However, while in case (i) this vector field is related to the symmetric part of the connection, in (ii) it comes from the torsion part and, therefore, it vanishes once torsion is completely removed. Moreover, the vanishing of this torsion-related vector field immediately implies the vanishing of the antisymmetric part of the Ricci tensor, which therefore plays no role in the dynamics. Related to this, we find that the Levi-Civita part of the connection is due to the existence of an invariant volume associated with an auxiliary metric h(mu v), which is algebraically related with the physical metric g(mu v). |
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Address |
[Olmo, Gonzalo J.] Ctr Mixto Univ Valencia CSIC, Dept Fis Teor, Valencia 46100, Spain, Email: gonzalo.olmo@csic.es; |
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Amer Physical Soc |
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English |
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1550-7998 |
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Notes |
WOS:000326107300007 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1630 |
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Author |
Bazeia, D.; Losano, L.; Olmo, G.J.; Rubiera-Garcia, D. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Black holes in five-dimensional Palatini f(R) gravity and implications for the AdS/CFT correspondence |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
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Volume |
90 |
Issue |
4 |
Pages |
044011 - 8pp |
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Abstract |
We show that theories having second-order field equations in the context of higher-dimensional modified gravity are not restricted to the family of Lovelock Lagrangians, but can also be obtained if no a priori assumption on the relation between the metric and affine structures of space-time is made (the Palatini approach). We illustrate this fact by considering the case of Palatini f(R) gravities in five dimensions. Our results provide an alternative avenue to explore new domains of the AdS/CFT correspondence without resorting to ad hoc quasitopological constructions. |
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Address |
[Bazeia, D.; Losano, L.; Olmo, Gonzalo J.; Rubiera-Garcia, D.] Univ Fed Paraiba, Dept Fis, BR-58051900 Joao Pessoa, Paraiba, Brazil, Email: bazeia@fisica.ufpb.br; |
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Amer Physical Soc |
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1550-7998 |
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Notes |
WOS:000339995400005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1863 |
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Permanent link to this record |
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Author |
Odintsov, S.D.; Olmo, G.J.; Rubiera-Garcia, D. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Born-Infeld gravity and its functional extensions |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
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Volume |
90 |
Issue |
4 |
Pages |
044003 - 8pp |
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Abstract |
We investigate the dynamics of a family of functional extensions of the (Eddington-inspired) Born-Infeld gravity theory, constructed with the inverse of the metric and the Ricci tensor. We provide a generic formal solution for the connection and an Einstein-like representation for the metric field equations of this family of theories. For particular cases we consider applications to the early-time cosmology and find that nonsingular universes with a cosmic bounce are very generic and robust solutions. |
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Address |
[Odintsov, Sergei D.] Inst Catalana Recerca & Estudis Avancats, Barcelona 08010, Spain, Email: gonzalo.olmo@csic.es; |
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Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Expedition |
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Conference |
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Notes |
WOS:000339999700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1880 |
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Permanent link to this record |
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Author |
Makarenko, A.N.; Odintsov, S.; Olmo, G.J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Born-Infeld f(R) gravity |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal ![sorted by Abbreviated Journal field, ascending order (up)](img/sort_asc.gif) |
Phys. Rev. D |
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Volume |
90 |
Issue |
2 |
Pages |
024066 - 15pp |
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Keywords |
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Abstract |
Motivated by the properties of matter quantum fields in curved space-times, we work out a gravity theory that combines the Born-Infeld gravity Lagrangian with an f(R) piece. To avoid ghostlike instabilities, the theory is formulated within the Palatini approach. This construction provides more freedom to address a number of important questions, such as the dynamics of the early Universe and the cosmic accelerated expansion, among others. In particular, we consider the effect that adding an f(R) = aR(2) term has on the early-time cosmology. We find that bouncing solutions are robust against these modifications of the Lagrangian whereas the solutions with loitering behavior of the original Born-Infeld theory are very sensitive to the R-2 term. In fact, these solutions are modified in such a way that a plateau in the H-2 function may arise, yielding a period of (approximately) de Sitter inflationary expansion. This inflationary behavior may be found even in a radiation-dominated universe. |
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Address |
[Makarenko, Andrey N.] Tomsk State Pedag Univ, Tomsk 634061, Russia |
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Publisher |
Amer Physical Soc |
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 |
1550-7998 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000341262300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1911 |
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Permanent link to this record |