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Author Bazeia, D.; Marques, M.A.; Olmo, G.J.
Title Small and hollow magnetic monopoles Type Journal Article
Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 98 Issue 2 Pages (down) 025017 - 8pp
Keywords
Abstract We deal with the presence of magnetic monopoles in a non-Abelian model that generalizes the standard 't Hooft-Polyakov model in three spatial dimensions. We investigate the energy density of the static and spherically symmetric solutions to find first order differential equations that solve the equations of motion. The system is further studied and two distinct classes of solutions are obtained, one that can also be described by analytical solutions and is called a small monopole, since it is significantly smaller than the standard 't Hooft-Polyakov monopole. The other type of structure is the hollow monopole, since the energy density is endowed with a hole at its core. The hollow monopole can be smaller or larger than the standard monopole, depending on the value of the parameter that controls the magnetic permeability of the model.
Address [Bazeia, D.; Marques, M. A.; Olmo, Gonzalo J.] Univ Fed Paraiba, Dept Fis, BR-58051970 Joao Pessoa, Paraiba, Brazil
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000439545000007 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3672
Permanent link to this record
 
 
Author Makarenko, A.N.; Odintsov, S.; Olmo, G.J.
Title Born-Infeld f(R) gravity Type Journal Article
Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 90 Issue 2 Pages (down) 024066 - 15pp
Keywords
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.
Address [Makarenko, Andrey N.] Tomsk State Pedag Univ, Tomsk 634061, Russia
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1550-7998 ISBN Medium
Area Expedition Conference
Notes WOS:000341262300003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1911
Permanent link to this record
 
 
Author Magalhaes, R.B.; Maso-Ferrando, A.; Olmo, G.J.; Crispino, L.C.B.
Title Asymmetric wormholes in Palatini f (R) gravity: Energy conditions, absorption, and quasibound states Type Journal Article
Year 2023 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 108 Issue 2 Pages (down) 024063 - 20pp
Keywords
Abstract We investigate the scalar absorption spectrum of wormhole solutions constructed via the recently developed thin-shell formalism for Palatini f(R) gravity. Such wormholes come from the matching of two Reissner-Nordstrom spacetimes at a timelike hypersurface (shell), which, according to the junction conditions in Palatini f(R), can be stable and have either positive or negative energy density. In particular, we identified a new physically interesting configuration made out of two overcharged Reissner-Nordstrom spacetimes, whose absorption profile departs from that of black holes and other previously considered wormholes in the whole range of frequencies. Unlike in symmetric wormhole solutions, the asymmetry of the effective potential causes the dilution of the resonances associated to the quasibound states for the high -frequency regime. Therefore, slight asymmetries in wormhole space-times could have a dramatic impact on the observable features associated to resonant states.
Address [Magalhaes, Renan B.; Crispino, Luis C. B.] Univ Fed, Programa Pos Graduacao Fis, BR-66075110 Belem, PA, Brazil, Email: renan.batalha@ext.uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:001055237800002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5629
Permanent link to this record
 
 
Author Olmo, G.J.; Rubiera-Garcia, D.; Wojnar, A.
Title Parameterized nonrelativistic limit of stellar structure equations in Ricci-based gravity theories Type Journal Article
Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 104 Issue 2 Pages (down) 024045 - 8pp
Keywords
Abstract We present the nonrelativistic limit of the stellar structure equations of Ricci-based gravities, a family of metric-affine theories whose Lagrangian is built via contractions of the metric with the Ricci tensor of an a priori independent connection. We find that this limit is characterized by four parameters that arise in the expansion of several geometric quantities in powers of the stress-energy tensor of the matter fields. We discuss the relevance of this result for the phenomenology of nonrelativistic stars, such as main-sequence stars as well as several substellar objects.
Address [Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, Ctr Mixto, CSIC, Valencia 46100, Spain, Email: gonzalo.olmo@uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000674579300010 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4914
Permanent link to this record
 
 
Author Lobo, F.S.N.; Martinez-Asencio, J.; Olmo, G.J.; Rubiera-Garcia, D.
Title Dynamical generation of wormholes with charged fluids in quadratic Palatini gravity Type Journal Article
Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 90 Issue 2 Pages (down) 024033 - 15pp
Keywords
Abstract The dynamical generation of wormholes within an extension of General Relativity (GR) containing (Planck's scale-suppressed) Ricci-squared terms is considered. The theory is formulated assuming the metric and connection to be independent (Palatini formalism) and is probed using a charged null fluid as a matter source. This has the following effect: starting from Minkowski space, when the flux is active the metric becomes a charged Vaidya-type one, and once the flux is switched off the metric settles down into a static configuration such that far from the Planck scale the geometry is virtually indistinguishable from that of the standard Reissner-Nordstrom solution of GR. However, the innermost region undergoes significant changes, as the GR singularity is generically replaced by a wormhole structure. Such a structure becomes completely regular for a certain charge-to-mass ratio. Moreover, the nontrivial topology of the wormhole allows us to define a charge in terms of lines of force trapped in the topology such that the density of lines flowing across the wormhole throat becomes a universal constant. In light of our results, we comment on the physical significance of curvature divergences in this theory and the topology change issue, which support the view that space-time could have a foamlike microstructure pervaded by wormholes generated by quantum gravitational effects.
Address [Lobo, Francisco S. N.] Univ Lisbon, Ctr Astron & Astrofis, P-1749016 Lisbon, Portugal, Email: flobo@cii.fc.ul.pt;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1550-7998 ISBN Medium
Area Expedition Conference
Notes WOS:000343305600009 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1979
Permanent link to this record
 
 
Author Silva, J.E.G.; Maluf, R.V.; Olmo, G.J.; Almeida, C.A.S.
Title Braneworlds in f(Q) gravity Type Journal Article
Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 106 Issue 2 Pages (down) 024033 - 15pp
Keywords
Abstract We propose a braneworld scenario in a modified symmetric teleparallel gravitational theory, where the dynamics for the gravitational field is encoded in the nonmetricity tensor rather than in the curvature. Assuming a single real scalar field with a sine-Gordon self-interaction, the generalized quadratic nonmetricity invariant Q controls the brane width while keeping the shape of the energy density. By considering power corrections of the invariant Q in the gravitational Lagrangian, the sine-Gordon potential is modified exhibiting new barriers and false vacuum. As a result, the domain wall brane obtains an inner structure, and it undergoes a splitting process. In addition, we also propose a nonminimal coupling between a bulk fermion field and the nonmetricity invariant Q. Such geometric coupling leads to a massless chiral fermion bound to the 3-brane and a stable tower of nonlocalized massive states.
Address [Silva, J. E. G.] Univ Fed do Cariri UFCA, Ave Tenente Raimundo Rocha,Cidade Universitaria, BR-63048080 Juazeiro do Norte, CE, Brazil, Email: euclides.silva@ufca.edu.br;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000880673200004 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5410
Permanent link to this record
 
 
Author Delhom, A.; Macedo, C.F.B.; Olmo, G.J.; Crispino, L.C.B.
Title Absorption by black hole remnants in metric-affine gravity Type Journal Article
Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 100 Issue 2 Pages (down) 024016 - 12pp
Keywords
Abstract Using numerical methods, we investigate the absorption properties of a family of nonsingular solutions which arise in different metric-affine theories, such as quadratic and Born-Infeld gravity. These solutions continuously interpolate between Schwarzschild black holes and naked solitons with wormhole topology. The resulting spectrum is characterized by a series of quasibound states excitations, associated with the existence of a stable photonsphere.
Address [Delhom, Adria; Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, Ctr Mixto Univ Valencia CSIC, E-46100 Valencia, Spain, Email: adna.delhom@uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000474874900007 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4075
Permanent link to this record
 
 
Author Alvarez-Ortega, D.; Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D.
Title Eternal versus singular observers in interacting dark-energy-dark-matter models Type Journal Article
Year 2022 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 106 Issue 2 Pages (down) 023523 - 14pp
Keywords
Abstract Interacting dark-energy-dark-matter models have been widely analyzed in the literature in an attempt to find traces of new physics beyond the usual cosmological (Lambda CDM) models. Such a coupling between both dark components is usually introduced in a phenomenological way through a flux in the continuity equation. However, models with a Lagrangian formulation are also possible. A class of the latter assumes a conformal/disformal coupling that leads to a fifth force on the dark-matter component, which consequently does not follow the same geodesics as the other (baryonic, radiation, and dark-energy) matter sources. Here we analyze how the usual cosmological singularities of the standard matter frame are seen from the dark-matter one, concluding that by choosing an appropriate coupling, dark-matter observers will see no singularities but a non beginning, non ending universe. By considering two simple phenomenological models we show that such a type of coupling can fit observational data as well as the usual Lambda CDM model.
Address [Alvarez-Ortega, Diego] Inst Fis Cantabria CSIC UC, Avda Castros S-N, Santander 39005, Spain, Email: diego.alvarezo@alumnos.unican.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000842768300012 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5345
Permanent link to this record
 
 
Author Afonso, V.I.; Olmo, G.J.; Rubiera-Garcia, D.
Title Mapping Ricci-based theories of gravity Into general relativity Type Journal Article
Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 97 Issue 2 Pages (down) 021503 - 6pp
Keywords
Abstract We show that the space of solutions of a wide class of Ricci-based metric-affine theories of gravity can be put into correspondence with the space of solutions of general relativity (GR). This allows us to use well-established methods and results from GR to explore new gravitational physics beyond it.
Address [Afonso, V. I.] Univ Fed Campina Grande, Unidade Acad Fis, BR-58109970 Campina Grande, PB, Brazil, Email: viafonso@df.ufcg.edu.br;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2470-0010 ISBN Medium
Area Expedition Conference
Notes WOS:000423656900001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3467
Permanent link to this record
 
 
Author Lobo, F.S.N.; Olmo, G.J.; Rubiera-Garcia, D.
Title Microscopic wormholes and the geometry of entanglement Type Journal Article
Year 2014 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 74 Issue 6 Pages (down) 2924 - 5pp
Keywords
Abstract It has recently been suggested that Einstein-Rosen (ER) bridges can be interpreted as maximally entangled states of two black holes that form a complex Einstein-Podolsky-Rosen (EPR) pair. This relationship has been dubbed as the correlation. In this work, we consider the latter conjecture in the context of quadratic Palatini theory. An important result, which stems from the underlying assumptions as regards the geometry on which the theory is constructed, is the fact that all the charged solutions of the quadratic Palatini theory possess a wormhole structure. Our results show that spacetime may have a foam-like microstructure with wormholes generated by fluctuations of the quantum vacuum. This involves the spontaneous creation/annihilation of entangled particle-antiparticle pairs, existing in a maximally entangled state connected by a non-traversable wormhole. Since the particles are produced from the vacuum and therefore exist in a singlet state, they are necessarily entangled with one another. This gives further support to the claim.
Address [Lobo, Francisco S. N.] Univ Lisbon, Ctr Astron & Astrofis, P-1749016 Lisbon, Portugal, Email: flobo@cii.fc.ul.pt;
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 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000337027100001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1814
Permanent link to this record