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Author Delhom, A.; Nascimento, J.R.; Olmo, G.J.; Petrov, A.Y.; Porfirio, P.J. url  doi
openurl 
  Title Radiative corrections in metric-affine bumblebee model Type Journal Article
  Year 2022 Publication (down) Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 826 Issue Pages 136932 - 9pp  
  Keywords  
  Abstract We consider the metric-affine formulation of bumblebee gravity, derive the field equations, and show that the connection can be written as Levi-Civita of a disformally related metric in which the bumblebee field determines the disformal part. As a consequence, the bumblebee field gets coupled to all the other matter fields present in the theory, potentially leading to nontrivial phenomenological effects. To explore this issue we compute the weak-field limit and study the resulting effective theory. In this scenario, we couple scalar and spinorial matter to the effective metric which, besides the zeroth-order Minkowskian contribution, also has the vector field contributions of the bumblebee, and show that it is renormalizable at one-loop level. From our analysis it also follows that the non-metricity of this theory is determined by the gradient of the bumblebee field, and that it can acquire a vacuum expectation value due to the contribution of the bumblebee field.  
  Address [Delhom, Adria; Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto, Dept Fis Teor, CSIC, Valencia 46100, Spain, Email: adria.delhom@uv.es;  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000792884500005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5229  
Permanent link to this record
 
 
Author Olmo, G.J.; Rubiera-Garcia, D.; Saez-Chillon Gomez, D. url  doi
openurl 
  Title New light rings from multiple critical curves as observational signatures of black hole mimickers Type Journal Article
  Year 2022 Publication (down) Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 829 Issue Pages 137045 - 5pp  
  Keywords  
  Abstract We argue that the appearance of additional light rings in a shadow observation – beyond the infinite sequence of exponentially demagnified self-similar rings foreseen in the Kerr solution – would make a compelling case for the existence of black hole mimickers having multiple critical curves. We support this claim by discussing three different scenarios of spherically symmetric wormhole geometries having two such critical curves, and explicitly work out the optical appearance of one such object when surrounded by an optically and geometrically thin accretion disk.  
  Address [Olmo, Gonzalo J.] Univ Valencia, CSIC, Ctr Mixto Univ Valencia, Dept Fis Teor, Valencia 46100, Spain, Email: gonzalo.olmo@uv.es;  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000821533700007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5290  
Permanent link to this record
 
 
Author Agullo, I.; Navarro-Salas, J.; Olmo, G.J.; Parker, L. url  doi
openurl 
  Title Hawking Radiation by Kerr Black Holes and Conformal Symmetry Type Journal Article
  Year 2010 Publication (down) Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 105 Issue 21 Pages 211305 - 4pp  
  Keywords  
  Abstract The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance.  
  Address [Agullo, Ivan; Parker, Leonard] Univ Wisconsin, Dept Phys, Milwaukee, WI 53201 USA  
  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 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000284407400004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 322  
Permanent link to this record
 
 
Author Barragan, C.; Olmo, G.J. url  doi
openurl 
  Title Isotropic and anisotropic bouncing cosmologies in Palatini gravity Type Journal Article
  Year 2010 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 82 Issue 8 Pages 084015 - 15pp  
  Keywords  
  Abstract We study isotropic and anisotropic (Bianchi I) cosmologies in Palatini f(R) and f(R, R μnu R μnu) theories of gravity with a perfect fluid and consider the existence of nonsingular bouncing solutions in the early universe. We find that all f(R) models with isotropic bouncing solutions develop shear singularities in the anisotropic case. On the contrary, the simple quadratic model R + aR(2)/R-P + R μnu R μnu/R-P exhibits regular bouncing solutions in both isotropic and anisotropic cases for a wide range of equations of state, including dust (for a<0) and radiation (for arbitrary a). It thus represents a purely gravitational solution to the big bang singularity and anisotropy problems of general relativity without the need for exotic (w>1) sources of matter/energy or extra degrees of freedom.  
  Address [Barragan, Carlos] Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, 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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000282751900002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 362  
Permanent link to this record
 
 
Author Agullo, I.; Navarro-Salas, J.; Olmo, G.J.; Parker, L. url  doi
openurl 
  Title Reply to "Comment on 'Insensitivity of Hawking radiation to an invariant Planck-scale cutoff' '' Type Journal Article
  Year 2010 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 81 Issue 10 Pages 108502 - 3pp  
  Keywords  
  Abstract We clarify the relationship between the conclusions of the previous Comment of A. Helfer [A. Helfer, preceding Comment, Phys. Rev. D 81, 108501 (2010)] and that of our Brief Report [I. Agullo, J. Navarro-Salas, G. J. Olmo, and L. Parker, Phys. Rev. D 80, 047503 (2009).].  
  Address [Agullo, Ivan; Olmo, Gonzalo J.; Parker, Leonard] Univ Wisconsin, Dept Phys, Milwaukee, WI 53201 USA  
  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 ISI:000278146700144 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 430  
Permanent link to this record
 
 
Author Agullo, I.; Navarro-Salas, J.; Olmo, G.J.; Parker, L. url  doi
openurl 
  Title Revising the observable consequences of slow-roll inflation Type Journal Article
  Year 2010 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 81 Issue 4 Pages 043514 - 14pp  
  Keywords  
  Abstract We study the generation of primordial perturbations in a (single-field) slow-roll inflationary Universe. In momentum space, these (Gaussian) perturbations are characterized by a zero mean and a nonzero variance Delta(2) (k, t). However, in position space the variance diverges in the ultraviolet. The requirement of a finite variance in position space forces one to regularize Delta(2) (k, t). This can (and should) be achieved by proper renormalization in an expanding Universe in a unique way. This affects the predicted scalar and tensorial power spectra (evaluated when the modes acquire classical properties) for wavelengths that today are at observable scales. As a consequence, the imprint of slow-roll inflation on the cosmic microwave background anisotropies is significantly altered. We find a nontrivial change in the consistency condition that relates the tensor-to-scalar ratio r to the spectral indices. For instance, an exact scale-invariant tensorial power spectrum, n(t) = 0, is now compatible with a nonzero ratio r approximate to 0.12 +/- 0.06, which is forbidden by the standard prediction (r = -8n(t)). The influence of relic gravitational waves on the cosmic microwave background may soon come within the range of planned measurements, offering a nontrivial test of the new predictions.  
  Address [Agullo, Ivan; Olmo, Gonzalo J.; Parker, Leonard] Univ Wisconsin, Dept Phys, Milwaukee, WI 53201 USA, Email: ivan.agullo@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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000275898500028 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 479  
Permanent link to this record
 
 
Author Olmo, G.J.; Sanchis-Alepuz, H. url  doi
openurl 
  Title Hamiltonian formulation of Palatini f(R) theories a la Brans-Dicke theory Type Journal Article
  Year 2011 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 83 Issue 10 Pages 104036 - 11pp  
  Keywords  
  Abstract We study the Hamiltonian formulation of f(R) theories of gravity both in metric and in Palatini formalism using their classical equivalence with Brans-Dicke theories with a nontrivial potential. The Palatini case, which corresponds to the omega = -3/2 Brans-Dicke theory, requires special attention because of new constraints associated with the scalar field, which is nondynamical. We derive, compare, and discuss the constraints and evolution equations for the omega = -3/2 and omega not equal -3/2 cases. Based on the properties of the constraint and evolution equations, we find that, contrary to certain claims in the literature, the Cauchy problem for the omega = -3/2 case is well formulated and there is no reason to believe that it is not well posed in general.  
  Address [Olmo, Gonzalo J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, 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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000290761400007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 631  
Permanent link to this record
 
 
Author Agullo, I.; Navarro-Salas, J.; Olmo, G.J.; Parker, L. url  doi
openurl 
  Title Remarks on the renormalization of primordial cosmological perturbations Type Journal Article
  Year 2011 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 84 Issue 10 Pages 107304 - 5pp  
  Keywords  
  Abstract We briefly review the need to perform renormalization of inflationary perturbations to properly work out the physical power spectra. We also summarize the basis of (momentum-space) renormalization in curved spacetime and address several misconceptions found in recent literature on this subject.  
  Address [Agullo, I] Penn State Univ, Dept Phys, Inst Gravitat & Cosmos, University Pk, PA 16802 USA  
  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:000297126700004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 811  
Permanent link to this record
 
 
Author Olmo, G.J.; Rubiera-Garcia, D. url  doi
openurl 
  Title Palatini f(R) black holes in nonlinear electrodynamics Type Journal Article
  Year 2011 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 84 Issue 12 Pages 124059 - 14pp  
  Keywords  
  Abstract The electrically charged Born-Infeld black holes in the Palatini formalism for f(R) theories are analyzed. Specifically we study those supported by a theory f(R) = R +/- R(2)/R(P), where R(P) is Planck's curvature. These black holes only differ from their General Relativity counterparts very close to the center but may give rise to different geometrical structures in terms of inner horizons. The nature and strength of the central singularities are also significantly affected. In particular, for the model f(R) = R – R(2)/R(P) the singularity is shifted to a finite radius, r(+), and the Kretschmann scalar diverges only as 1/(r-r(+))(2).  
  Address [Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto Univ Valencia CSIC, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000298666600005 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 878  
Permanent link to this record
 
 
Author Harko, T.; Koivisto, T.S.; Lobo, F.S.N.; Olmo, G.J. url  doi
openurl 
  Title Metric-Palatini gravity unifying local constraints and late-time cosmic acceleration Type Journal Article
  Year 2012 Publication (down) Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 85 Issue 8 Pages 084016 - 5pp  
  Keywords  
  Abstract We present a novel approach to modified theories of gravity which consists of adding to the Einstein-Hilbert Lagrangian an f(R) term constructed a la Palatini. Using the respective dynamically equivalent scalar-tensor representation, we show that the theory can pass the Solar System observational constraints even if the scalar field is very light. This implies the existence of a long-range scalar field, which is able to modify the cosmological and galactic dynamics but leaves the Solar System unaffected. We also verify the absence of instabilities in perturbations and provide explicit models which are consistent with local tests and lead to the late-time cosmic acceleration.  
  Address [Harko, Tiberiu] Univ Hong Kong, Dept Phys, Hong Kong, Hong Kong, Peoples R China, Email: harko@hkucc.hku.hk;  
  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:000302996100011 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 996  
Permanent link to this record
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