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Author |
Magalhaes, R.B.; Ribeiro, G.P.; Lima, H.C.D.J.; Olmo, G.J.; Crispino, L.C.B. |
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Title |
Singular space-times with bounded algebraic curvature scalars |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
05 |
Issue |
5 |
Pages  |
114 - 34pp |
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Keywords |
gravity; modified gravity; Wormholes |
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Abstract |
We show that the absence of unbounded algebraic curvature invariants constructed from polynomials of the Riemann tensor cannot guarantee the absence of strong singularities. As a consequence, it is not sufficient to rely solely on the analysis of such scalars to assess the regularity of a given space-time. This conclusion follows from the analysis of incomplete geodesics within the internal region of asymmetric wormholes supported by scalar matter which arise in two distinct metric-affine gravity theories. These wormholes have bounded algebraic curvature scalars everywhere, which highlights that their finiteness does not prevent the emergence of pathologies (singularities) in the geodesic structure of space-time. By analyzing the tidal forces in the internal wormhole region, we find that the angular components are unbounded along incomplete radial time-like geodesics. The strength of the singularity is determined by the evolution of Jacobi fields along such geodesics, finding that it is of strong type, as volume elements are torn apart as the singularity is approached. Lastly, and for completeness, we consider the wormhole of the quadratic Palatini theory and present an analysis of the tidal forces in the entire space-time. |
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Address |
[Magalhaes, Renan B.; Ribeiro, Gabriel P.; Lima Jr, Haroldo C. D.; Crispino, Luis C. B.] Univ Fed Para, Programa Posgrad Fis, BR-66075110 Belem, Para, Brazil, Email: renan.magalhaes@icen.ufpa.br; |
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IOP Publishing Ltd |
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English |
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ISSN |
1475-7516 |
ISBN |
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Conference |
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Notes |
WOS:001265908300012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6200 |
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Author |
Lessa, L.A.; Maluf, R.V.; Silva, J.E.G.; Almeida, C.A.S. |
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Title |
Braneworlds in warped Einsteinian cubic gravity |
Type |
Journal Article |
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Year |
2024 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
05 |
Issue |
5 |
Pages |
123 - 25pp |
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Keywords |
Gauss-Bonnet-Lovelock-Horndeski-Palatini etc gravity theories; gravity; modified gravity |
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Abstract |
Einstenian cubic gravity (ECG) is a modified theory of gravity constructed with cubic contractions of the curvature tensor. This theory has the remarkable feature of having the same two propagating degrees of freedom of Einstein gravity (EG), at the perturbative level on maximally symmetric spacetimes. The additional unstable modes steaming from the higher order derivative dynamics are suppressed provided that we consider the ECG as an effective field theory wherein the cubic terms are seen as perturbative corrections of the Einstein -Hilbert term. Extensions of ECG have been proposed in cosmology and compact objects in order to probe if this property holds in more general configurations. In this work, we construct a modified ECG gravity in a five dimensional warped braneworld scenario. By assuming a specific combination of the cubic parameters, we obtained modified gravity equations of motion with terms up to second -order. For a thin 3-brane, the cubic -gravity corrections yield an effective positive bulk cosmological constant. Thus, in order to keep the 5D bulk warped compact, an upper bound of the cubic parameter with respect to the bulk curvature was imposed. For a thick brane, the cubic -gravity terms modify the scalar field potential and its corresponding vacuum. Nonetheless, the domain -wall structure with a localized source is preserved. At the perturbative level, the Kaluza-Klein (KK) tensor gravitational modes are stable and possess a localized massless mode provided the cubic corrections are small compared to the EG braneworld. |
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Address |
[Lessa, L. A.; Maluf, R. V.; Silva, J. E. G.; Almeida, C. A. S.] Univ Fed Ceara UFC, Dept Fis, Campus Pici, BR-60455760 Fortaleza, CE, Brazil, Email: leandrolessa@fisica.ufc.br; |
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IOP Publishing Ltd |
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English |
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ISSN |
1475-7516 |
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Conference |
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Notes |
WOS:001240966600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6164 |
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Author |
ANTARES Collaboration (Aguilar, J.A. et al); Bigongiari, C.; Dornic, D.; Emanuele, U.; Gomez-Gonzalez, J.P.; Hernandez-Rey, J.J.; Mangano, S.; Salesa, F.; Toscano, S.; Yepes, H.; Zornoza, J.D.; Zuñiga, J. |
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Title |
Zenith distribution and flux of atmospheric muons measured with the 5-line ANTARES detector |
Type |
Journal Article |
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Year |
2010 |
Publication |
Astroparticle Physics |
Abbreviated Journal |
Astropart Phys. |
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Volume |
34 |
Issue |
3 |
Pages |
179-184 |
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Keywords |
Atmospheric muons; Neutrino telescope; Depth-intensity relation |
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Abstract |
The ANTARES high-energy neutrino telescope is a three-dimensional array of about 900 photomultipliers distributed over 12 mooring lines installed in the Mediterranean Sea. Between February and November 2007 it acquired data in a 5-line configuration. The zenith angular distribution of the atmospheric muon flux and the associated depth-intensity relation are measured and compared with previous measurements and Monte Carlo expectations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is presented. |
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Address |
[Bazzotti, M.; Biagi, S.; Carminati, G.; Giacomelli, G.; Margiotta, A.; Spurio, M.] Dipartimento Fis Univ, I-40127 Bologna, Italy, Email: Annarita.Margiotta@bo.infn.it |
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Publisher |
Elsevier Science Bv |
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English |
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Series Volume |
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ISSN |
0927-6505 |
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Notes |
ISI:000282496000005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
373 |
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Author |
ANTARES Collaboration (Adrian-Martinez, S. et al); Bigongiari, C.; Dornic, D.; Emanuele, U.; Gomez-Gonzalez, J.P.; Hernandez-Rey, J.J.; Lambard, G.; Mangano, S.; Ruiz-Rivas, J.; Salesa, F.; Sanchez-Losa, A.; Toscano, S.; Yepes, H.; Zornoza, J.D.; Zuñiga, J. |
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Title |
Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope |
Type |
Journal Article |
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Year |
2012 |
Publication |
Astroparticle Physics |
Abbreviated Journal |
Astropart Phys. |
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Volume |
36 |
Issue |
1 |
Pages |
204-210 |
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Keywords |
ANTARES; Neutrino astronomy; Fermi LAT transient sources; Time-dependent search; Blazars |
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Abstract |
The ANTARES telescope is well-suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. Radio-loud active galactic nuclei with jets pointing almost directly towards the observer, the so-called blazars, are particularly attractive potential neutrino point sources. The all-sky monitor LAT on board the Fermi satellite probes the variability of any given gamma-ray bright blazar in the sky on time scales of hours to months. Assuming hadronic models, a strong correlation between the gamma-ray and the neutrino fluxes is expected. Selecting a narrow time window on the assumed neutrino production period can significantly reduce the background. An unbinned method based on the minimization of a likelihood ratio was applied to a subsample of data collected in 2008 (61 days live time). By searching for neutrinos during the high state periods of the AGN light curve, the sensitivity to these sources was improved by about a factor of two with respect to a standard time-integrated point source search. First results on the search for neutrinos associated with ten bright and variable Fermi sources are presented. |
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Address |
[Al Samarai, I.; Aubert, J-J.; Bertin, V.; Brunner, J.; Busto, J.; Carr, J.; Charif, Z.; Core, L.; Costantini, H.; Coyle, P.; Curtil, C.; Dornic, D.; Ernenwein, J-P.; Escoffier, S.; Galata, S.; Halladjian, G.; Hallewell, G.; Payre, P.; Picot-Clemente, N.; Riviere, C.; Vallee, C.; Vecchi, M.] Aix Marseille Univ, CPPM, CNRS, IN2P3, Marseille, France, Email: dornic@in2p3.fr |
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Publisher |
Elsevier Science Bv |
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English |
Summary Language |
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ISSN |
0927-6505 |
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Conference |
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Notes |
WOS:000309787000024 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1190 |
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Author |
Pierre Auger Collaboration (Abreu, P. et al); Pastor, S. |
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Title |
The Lateral Trigger Probability function for the Ultra-High Energy Cosmic Ray showers detected by the Pierre Auger Observatory |
Type |
Journal Article |
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Year |
2011 |
Publication |
Astroparticle Physics |
Abbreviated Journal |
Astropart Phys. |
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Volume |
35 |
Issue |
5 |
Pages |
266-276 |
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Keywords |
Ultra-High Energy Cosmic Rays; Pierre Auger Observatory; Extensive Air Showers; Trigger performance; Surface detector; Hybrid detector |
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Abstract |
In this paper we introduce the concept of Lateral Trigger Probability (LTP) function, i.e., the probability for an Extensive Air Shower (EAS) to trigger an individual detector of a ground based array as a function of distance to the shower axis, taking into account energy, mass and direction of the primary cosmic ray. We apply this concept to the surface array of the Pierre Auger Observatory consisting of a 1.5 km spaced grid of about 1600 water Cherenkov stations. Using Monte Carlo simulations of ultra-high energy showers the LTP functions are derived for energies in the range between 10(17) and 10(19) eV and zenith angles up to 65 degrees. A parametrization combining a step function with an exponential is found to reproduce them very well in the considered range of energies and zenith angles. The LTP functions can also be obtained from data |
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Address |
[Abreu, P.; Andringa, S.; Assis, P.; Brogueira, P.; Cazon, L.; Conceicao, R.; Goncalves, P.; Pimenta, M.; Santo, C. E.; Santos, E.; Tome, B.] LIP, P-1000 Lisbon, Portugal, Email: auger_spokespersons@fnal.gov |
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Publisher |
Elsevier Science Bv |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
0927-6505 |
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Conference |
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Notes |
WOS:000297434500006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
837 |
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