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Author Bazeia, D.; Losano, L.; Olmo, G.J.; Rubiera-Garcia, D.
Title Geodesically complete BTZ-type solutions of 2+1 Born-Infeld gravity Type Journal Article
Year 2017 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity
Volume 34 Issue 4 Pages 045006 - 21pp
Keywords (up) Born-Infeld gravity; BTZ; wormholes; nonsingular solutions; geodesic completeness
Abstract We study Born-Infeld gravity coupled to a static, non-rotating electric field in 2 + 1 dimensions and find exact analytical solutions. Two families of such solutions represent geodesically complete, and hence nonsingular, spacetimes. Another family represents a point-like charge with a singularity at the center. Despite the absence of rotation, these solutions resemble the charged, rotating BTZ solution of general relativity but with a richer structure in terms of horizons. The nonsingular character of the first two families turn out to be attached to the emergence of a wormhole structure on their innermost region. This seems to be a generic prediction of extensions of general relativity formulated in metric-affine (or Palatini) spaces, where metric and connection are regarded as independent degrees of freedom.
Address [Bazeia, D.; Losano, L.; Olmo, Gonzalo J.] Univ Fed Paraiba, Dept Fis, BR-58051900 Joao Pessoa, Paraiba, Brazil, Email: bazeia@fisica.ufpb.br;
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0264-9381 ISBN Medium
Area Expedition Conference
Notes WOS:000395398800002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3013
Permanent link to this record
 
 
Author Maso-Ferrando, A.; Sanchis-Gual, N.; Font, J.A.; Olmo, G.J.
Title Boson stars in Palatini f(R) gravity Type Journal Article
Year 2021 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity
Volume 38 Issue 19 Pages 194003 - 25pp
Keywords (up) boson stars; Palatini formalism; modified gravity
Abstract We explore equilibrium solutions of spherically symmetric boson stars in the Palatini formulation of f (R) gravity. We account for the modifications introduced in the gravitational sector by using a recently established correspondence between modified gravity with scalar matter and general relativity with modified scalar matter. We focus on the quadratic theory f (R) = R + xi R-2 and compare its solutions with those found in general relativity, exploring both positive and negative values of the coupling parameter xi. As matter source, a complex, massive scalar field with and without self-interaction terms is considered. Our results show that the existence curves of boson stars in Palatini f (R) gravity are fairly similar to those found in general relativity. Major differences are observed for negative values of the coupling parameter which results in a repulsive gravitational component for high enough scalar field density distributions. Adding self-interactions makes the degeneracy between f (R) and general relativity even more pronounced, leaving very little room for observational discrimination between the two theories.
Address [Maso-Ferrando, Andreu; Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, Ctr Mixto Univ Valencia CSIC, Valencia 46100, Spain, Email: andreu.maso@uv.es
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0264-9381 ISBN Medium
Area Expedition Conference
Notes WOS:000695280300001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4964
Permanent link to this record
 
 
Author Araujo Filho, A.A.; Hassanabadi, H.; Heidari, N.; Kriz, J.; Zare, S.
Title Gravitational traces of bumblebee gravity in metric-affine formalism Type Journal Article
Year 2024 Publication Classical and Quantum Gravity Abbreviated Journal Class. Quantum Gravity
Volume 41 Issue 5 Pages 055003 - 21pp
Keywords (up) bumblebee gravity; metric affine formalism; shadows
Abstract This work explores various manifestations of bumblebee gravity within the metric-affine formalism. We investigate the impact of the Lorentz violation parameter, denoted as X, on the modification of the Hawking temperature. Our calculations reveal that as X increases, the values of the Hawking temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the quasinormal modes, we employ the Wentzel-Kramers-Brillouin method. The transmission and reflection coefficients are determined through our calculations. The outcomes indicate that a stronger Lorentz-violating parameter results in slower damping oscillations of gravitational waves. To comprehend the influence of the quasinormal spectrum on time-dependent scattering phenomena, we present a detailed analysis of scalar perturbations in the time-domain solution. Additionally, we conduct an investigation on shadows, revealing that larger values of X correspond to larger shadow radii. Furthermore, we constrain the magnitude of the shadow radii using the EHT horizon-scale image of SgrA* . Finally, we calculate both the time delay and the deflection angle.
Address [Araujo Filho, A. A.] Univ Valencia, CSIC, Dept Fis Teor, Ctr MIxto Univ Valencia, Burjassot 46100, Valencia, Spain, Email: dilto@fisica.ufc.br
Corporate Author Thesis
Publisher IOP Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0264-9381 ISBN Medium
Area Expedition Conference
Notes WOS:001152994800001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5925
Permanent link to this record
 
 
Author Capozziello, S.; Harko, T.; Lobo, F.S.N.; Olmo, G.J.; Vignolo, S.
Title The Cauchy problem in hybrid metric-Palatini f(X)-gravity Type Journal Article
Year 2014 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.
Volume 11 Issue 5 Pages 1450042 - 12pp
Keywords (up) Cauchy problem; modified gravity; hybrid metric-Palatini gravity
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.
Address [Capozziello, Salvatore] Univ Naples Federico II, Dipartimento Sci Fis, Naples, Italy, Email: capozzie@na.infn.it;
Corporate Author Thesis
Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0219-8878 ISBN Medium
Area Expedition Conference
Notes WOS:000336527100003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1813
Permanent link to this record
 
 
Author Delhom, A.; Olmo, G.J.; Orazi, E.
Title Ricci-Based Gravity theories and their impact on Maxwell and nonlinear electromagnetic models Type Journal Article
Year 2019 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 11 Issue 11 Pages 149 - 24pp
Keywords (up) Classical Theories of Gravity; Beyond Standard Model
Abstract We extend the correspondence between metric-affine Ricci-Based Gravity the- ories and General Relativity (GR) to the case in which the matter sector is represented by linear and nonlinear electromagnetic fields. This complements previous studies focused on fluids and scalar fields. We establish the general algorithm that relates the matter fields in the GR and RBG frames and consider some applications. In particular, we find that the so-called Eddington-inspired Born-Infeld gravity theory coupled to Maxwell electromag- netism is in direct correspondence with GR coupled to Born-Infeld electromagnetism. We comment on the potential phenomenological implications of this relation.
Address [Delhom, Adria; Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: adria.delhom@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000513489000001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4281
Permanent link to this record
 
 
Author Babichev, E.; Fabbri, A.
Title A class of charged black hole solutions in massive (bi)gravity Type Journal Article
Year 2014 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 07 Issue 7 Pages 016 - 10pp
Keywords (up) Classical Theories of Gravity; Black Holes
Abstract We present a new class of solutions describing charged black holes in massive (bi)gravity. For a generic choice of the parameters of the massive gravity action, the solution is the Reissner-Nordstrom-de Sitter metric written in the Eddington-Finkelstein coordinates for both metrics. We also study a special case of the parameters, for which the space of solutions contains an extra symmetry.
Address [Babichev, Eugeny] Univ Paris 11, CNRS, LPT, UMR 8627, F-91405 Orsay, France, Email: eugeny.babichev@th.u-psud.fr;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000339110500001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1847
Permanent link to this record
 
 
Author Foffa, S.; Sturani, R.; Torres Bobadilla, W.J.
Title Efficient resummation of high post-Newtonian contributions to the binding energy Type Journal Article
Year 2021 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 02 Issue 2 Pages 165 - 18pp
Keywords (up) Classical Theories of Gravity; Black Holes; Effective Field Theories
Abstract A factorisation property of Feynman diagrams in the context the Effective Field Theory approach to the compact binary problem has been recently employed to efficiently determine the static sector of the potential at fifth post-Newtonian (5PN) order. We extend this procedure to the case of non-static diagrams and we use it to fix, by means of elementary algebraic manipulations, the value of more than one thousand diagrams at 5PN order, that is a substantial fraction of the diagrams needed to fully determine the dynamics at 5PN. This procedure addresses the redundancy problem that plagues the computation of the binding energy with respect to more “efficient” observables like the scattering angle, thus making the EFT approach in harmonic gauge at least as scalable as the others methods.
Address [Foffa, Stefano] Univ Geneva, Dept Phys Theor, CH-1211 Geneva, Switzerland, Email: stefano.foffa@unige.ch;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000621231300003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4740
Permanent link to this record
 
 
Author Bellomo, N.; Bellini, E.; Hu, B.; Jimenez, R.; Pena-Garay, C.; Verde, L.
Title Hiding neutrino mass in modified gravity cosmologies Type Journal Article
Year 2017 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.
Volume 02 Issue 2 Pages 043 - 12pp
Keywords (up) cosmological neutrinos; modified gravity; neutrino astronomy; neutrino masses from cosmology
Abstract Cosmological observables show a dependence with the neutrino mass, which is partially degenerate with parameters of extended models of gravity. We study and explore this degeneracy in Horndeski generalized scalar-tensor theories of gravity. Using forecasted cosmic microwave background and galaxy power spectrum datasets, we find that a single parameter in the linear regime of the effective theory dominates the correlation with the total neutrino mass. For any given mass, a particular value of this parameter approximately cancels the power suppression due to the neutrino mass at a given redshift. The extent of the cancellation of this degeneracy depends on the cosmological large-scale structure data used at different redshifts. We constrain the parameters and functions of the effective gravity theory and determine the influence of gravity on the determination of the neutrino mass from present and future surveys.
Address [Bellomo, Nicola; Bellini, Emilio; Hu, Bin; Jimenez, Raul; Verde, Licia] Univ Barcelona UB IEEC, ICC, Marti & Franques 1, Barcelona 08028, Spain, Email: nicola.bellomo@icc.ub.edu;
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1475-7516 ISBN Medium
Area Expedition Conference
Notes WOS:000399455000043 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3078
Permanent link to this record
 
 
Author Lazaries, G.; Pallis, C.
Title Shift symmetry and Higgs inflation in supergravity with observable gravitational waves Type Journal Article
Year 2015 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 11 Issue 11 Pages 114 - 28pp
Keywords (up) Cosmology of Theories beyond the SM; Supergravity Models; Supersymmetric Effective Theories
Abstract We demonstrate how to realize within supergravity a novel chaotic-type inflationary scenario driven by the radial parts of a conjugate pair of Higgs superfields causing the spontaneous breaking of a grand unified gauge symmetry at a scale assuming the value of the supersymmetric grand unification scale. The superpotential is uniquely determined at the renormalizable level by the gauge symmetry and a continuous R symmetry. We select two types of Kahler potentials, which respect these symmetries as well as an approximate shift symmetry. In particular, they include in a logarithm a dominant shift-symmetric term proportional to a parameter c together with a small term violating this symmetry and characterized by a parameter c(+). In both cases, imposing a lower bound on c, inflation can be attained with subplanckian values of the original inflaton, while the corresponding effective theory respects perturbative unitarity for r +/- = c(+)/c_ <= 1. These inflationary models do not lead to overproduction of cosmic defects, are largely independent of the one-loop radiative corrections and accommodate, for natural values of r +/-, observable gravitational waves consistently with all the current observational data. The inflaton mass is mostly confined in the range (3.7 – 8.1) x 10(10) GeV.
Address [Lazaries, G.] Aristotle Univ Thessaloniki, Fac Engn, Sch Elect & Comp Engn, GR-54124 Thessaloniki, Greece, Email: lazaride@eng.auth.gr;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000365101200001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2467
Permanent link to this record
 
 
Author Borja, E.F.; Garay, I.; Vidotto, F.
Title Learning about Quantum Gravity with a Couple of Nodes Type Journal Article
Year 2012 Publication Symmetry Integrability and Geometry-Methods and Applications Abbreviated Journal Symmetry Integr. Geom.
Volume 8 Issue Pages 015 - 44pp
Keywords (up) discrete gravity; canonical quantization; spinors; spinfoam; quantum cosmology
Abstract Loop Quantum Gravity provides a natural truncation of the infinite degrees of freedom of gravity, obtained by studying the theory on a given finite graph. We review this procedure and we present the construction of the canonical theory on a simple graph, formed by only two nodes. We review the U(N) framework, which provides a powerful tool for the canonical study of this model, and a formulation of the system based on spinors. We consider also the covariant theory, which permits to derive the model from a more complex formulation, paying special attention to the cosmological interpretation of the theory.
Address [Borja, Enrique F.; Garay, Inaki] Univ Erlangen Nurnberg, Inst Theoret Phys 3, D-91058 Erlangen, Germany, Email: efborja@theorie3.physik.uni-erlangen.de;
Corporate Author Thesis
Publisher Natl Acad Sci Ukraine, Inst Math Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1815-0659 ISBN Medium
Area Expedition Conference
Notes WOS:000303831400001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1018
Permanent link to this record