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Author |
Olmo, G.J. |
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Title |
Birkhoff's theorem and perturbations in f(R) theories |
Type |
Journal Article |
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Year |
2012 |
Publication |
Annalen der Physik |
Abbreviated Journal |
Ann. Phys.-Berlin |
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Volume |
524 |
Issue  |
5 |
Pages |
87-88 |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, Fac Fis, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@uv.es |
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Publisher |
Wiley-V C H Verlag Gmbh |
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Language |
English |
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ISSN |
0003-3804 |
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Notes |
WOS:000303662900008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1013 |
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Author |
Capozziello, S.; Harko, T.; Lobo, F.S.N.; Olmo, G.J.; Vignolo, S. |
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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 |
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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Language |
English |
Summary Language |
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Series Volume |
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Edition |
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ISSN |
0219-8878 |
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Conference |
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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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Author |
Olmo, G.J.; Rubiera-Garcia, D.; Sanchez-Puente, A. |
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Title |
Accelerated observers and the notion of singular spacetime |
Type |
Journal Article |
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Year |
2018 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
35 |
Issue |
5 |
Pages |
055010 - 18pp |
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Keywords |
general relativity; geodesic behaviour; black holes; spacetime singularities; modified theories of gravity |
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Abstract |
Geodesic completeness is typically regarded as a basic criterion to determine whether a given spacetime is regular or singular. However, the principle of general covariance does not privilege any family of observers over the others and, therefore, observers with arbitrary motions should be able to provide a complete physical description of the world. This suggests that in a regular spacetime, all physically acceptable observers should have complete paths. In this work we explore this idea by studying the motion of accelerated observers in spherically symmetric spacetimes and illustrate it by considering two geodesically complete black hole spacetimes recently described in the literature. We show that for bound and locally unbound accelerations, the paths of accelerated test particles are complete, providing further support to the regularity of such spacetimes. |
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Address |
[Olmo, Gonzalo J.; Sanchez-Puente, Antonio] Univ Valencia, Dept Fis Teor, CSIC, Ctr Mixto, E-46100 Valencia, Spain, Email: gonzalo.olmo@uv.es; |
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Publisher |
Iop Publishing Ltd |
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English |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0264-9381 |
ISBN |
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Conference |
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Notes |
WOS:000424042100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3473 |
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Author |
Izadi, A.; Shacker, S.S.; Olmo, G.J.; Banerjee, R. |
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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 |
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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Publisher |
World Scientific Publ Co Pte Ltd |
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Language |
English |
Summary Language |
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Original 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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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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Author |
Delhom, A.; Lobo, I.P.; Olmo, G.J.; Romero, C. |
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Title |
Conformally invariant proper time with general non-metricity |
Type |
Journal Article |
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Year |
2020 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
80 |
Issue |
5 |
Pages |
415 - 11pp |
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Keywords |
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Abstract |
We show that the definition of proper time for Weyl-invariant space-times given by Perlick naturally extends to spaces with arbitrary non-metricity. We then discuss the relation between this generalized proper time and the Ehlers-Pirani-Schild definition of time when there is arbitrary non-metricity. Then we show how this generalized proper time suffers from a second clock effect. Assuming that muons are a device to measure this proper time, we constrain the non-metricity tensor on Earth's surface and then elaborate on the feasibility of such assumption. |
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Address |
[Delhom, Adria] Univ Valencia, Ctr Mixto Univ Valencia, Dept Fis Teor, CSIC, Valencia 46100, Spain, Email: adria.delhom@uv.es; |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Language |
English |
Summary Language |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
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Conference |
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Notes |
WOS:000535820900011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4405 |
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