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Author |
Carles, M.; Lerche, C.W.; Sanchez, F.; Mora, F.; Benlloch, J.M. |
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Title |
Position correction with depth of interaction information for a small animal PET system |
Type |
Journal Article |
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Year |
2011 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
648 |
Issue |
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Pages |
S176-S180 |
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Keywords |
DOI; PET; Positioning algorithm; Gamma ray imaging; Continuous scintillators |
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Abstract |
In this work we study the effects on the spatial resolution when depth of interaction (001) information is included in the parameterization of the line of response (LOR) for a small animal positron emission tomography (PET) system. One of the most important degrading factors for PET is the parallax error introduced in systems that do not provide DOI information of the recorded gamma-rays. Our group has designed a simple and inexpensive method for DOI determination in continuous scintillation crystals. This method is based, on one hand, in the correlation between the scintillation light distribution width in monolithic crystals and the DOI, and, on the other hand, on a small modification of the widely applied charge dividing circuits (CDR). In this work we present a new system calibration that includes the DOI information, and also the development of the correction equations that relates the LOR without and with DOI information. We report the results obtained for different measurements along the transaxial field of view (FOV) and the image quality enhancement achieved specially at the edge of the FOV. |
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Address |
[Carles, M.; Sanchez, F.; Benlloch, J. M.] Inst Fis Corpuscular CSIC UV, Valencia 46071, Spain, Email: montcar@ific.uv.es |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0168-9002 |
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Conference |
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Notes |
WOS:000305376900046 |
Approved |
no |
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Is ISI |
yes |
International Collaboration  |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1067 |
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Author |
Soriano, A.; Gonzalez, A.; Orero, A.; Moliner, L.; Carles, M.; Sanchez, F.; Benlloch, J.M.; Correcher, C.; Carrilero, V.; Seimetz, M. |
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Title |
Attenuation correction without transmission scan for the MAMMI breast PET |
Type |
Journal Article |
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Year |
2011 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
648 |
Issue |
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Pages |
S75-S78 |
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Keywords |
Breast PET; Attenuation correction |
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Abstract |
Whole-body Positron Emission Tomography (PET) scanners are required in order to span large Fields of View (FOV). Therefore, reaching the sensitivity and spatial resolution required for early stage breast tumor detection is not straightforward. MAMMI is a dedicated breast PET scanner with a ring geometry designed to provide PET images with a spatial resolution as high as 1.5 mm, being able to detect small breast tumors ( < 1 cm). The patient lays down in prone position during the scan, thus making possible to image the whole breast, up to regions close to the base of the pectoral without the requirement of breast compression. Attenuation correction (AC) for PET data improves the image quality and the quantitative accuracy of radioactivity distribution determination. In dedicated, high resolution breast cancer scanners, this correction would enhance the proper diagnosis in early disease stages. In whole-body PET scanners, AC is usually taken into account with the use of transmission scans, either by external radioactive rod sources or by Computed Tomography (CT). This considerably increases the radiation dose administered to the patient and time needed for the exploration. In this work we propose a method for breast shape identification by means of PET image segmentation. The breast shape identification will be used for the determination of the AC. For the case of a specific breast PET scanner the procedure we propose should provide AC similar to that obtained by transmission scans as we take advantage of the breast anatomical simplicity. Experimental validation of the proposed approach with a dedicated breast PET prototype is also presented. The main advantage of this method is an important dose reduction since the transmission scan is not required. |
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Address |
[Soriano, A.; Orero, A.; Moliner, L.; Carles, M.; Sanchez, F.; Benlloch, J. M.] Univ Valencia, CSIC, Inst Fis Corpuscular, E-46980 Paterna, Spain, Email: soriano@ific.uv.es |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0168-9002 |
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Expedition |
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Conference |
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Notes |
WOS:000305376900021 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1069 |
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Author |
Bandos, I.A.; de Azcarraga, J.A.; Meliveo, C. |
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Title |
Conformal higher spin theory in extended tensorial superspace |
Type |
Journal Article |
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Year |
2012 |
Publication |
Fortschritte der Physik-Progress of Physics |
Abbreviated Journal |
Fortschritte Phys.-Prog. Phys. |
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Volume |
60 |
Issue |
7-8 |
Pages |
861-867 |
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Keywords |
Higher spin theory; conformal symmetry; superfields; tensorial superspaces |
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Abstract |
We discuss the formulation of free conformal higher spin theories with extended N = 2, 4, 8 supersymmetry in N-extended tensorial superspaces. The superfield higher spin equations can be obtained by quantizing a superparticle model in N-extended tensorial superspace. The N-extended higher spin supermultiplets just contain scalar and spinor fields in tensorial space so that, in contrast with the standard (super)space approach, no nontrivial generalizations of the Maxwell or Einstein equations to tensorial space appear when N > 2. For N = 4, 8, the higher spin-tensorial components of the extended tensorial superfields are expressed through additional scalar and spinor fields in tensorial space which obey the same free higher spin equations, but that are axion-like in the sense that they possess Peccei-Quinn-like symmetries. |
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Address |
[Bandos, Igor A.; Meliveo, Carlos] Univ Basque Country UPV EHU, Dept Theoret Phys, Bilbao 48080, Spain, Email: carlos_meliveo@ehu.es |
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Publisher |
Wiley-V C H Verlag Gmbh |
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Language |
English |
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Edition |
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ISSN |
0015-8208 |
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Expedition |
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Conference |
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Notes |
WOS:000306357900010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1095 |
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Author |
Aceti, F.; Oset, E. |
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Title |
Wave functions of composite hadron states and relationship to couplings of scattering amplitudes for general partial waves |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
86 |
Issue |
1 |
Pages |
014012 - 12pp |
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Keywords |
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Abstract |
In this paper we present the connection between scattering amplitudes in momentum space and wave functions in coordinate space, generalizing previous work done for s-waves to any partial wave. The relationship to the wave function of the residues of the scattering amplitudes at the pole of bound states or resonances is investigated in detail. A sum rule obtained for the couplings provides a generalization to coupled channels, any partial wave and bound or resonance states, of Weinberg's compositeness condition, which was only valid for weakly bound states in one channel and s-wave. An example, requiring only experimental data, is shown for the rho meson indicating that it is not a composite particle of pi pi and K (K) over bar but something else. |
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Address |
[Aceti, F.] Univ Valencia, Ctr Mixto, CSIC, Dept Fis Teor,Inst Invest Paterna, Valencia 46071, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
1550-7998 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000306319500003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1099 |
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Author |
Molina, R.; Xiao, C.W.; Oset, E. |
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Title |
J/psi reaction mechanisms and suppression in the nuclear medium |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
86 |
Issue |
1 |
Pages |
014604 - 9pp |
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Keywords |
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Abstract |
Recent studies of the interaction of vector mesons with nuclei make possible and opportune the study of the interaction of the J/psi with nuclei and the investigation of the origin of the J/psi suppression in its propagation thorough a nuclear medium. We observe that the transition of J/psi N to VN with V being a light vector, rho, omega, phi, together with the inelastic channels, J/psi N -> (D) over bar Lambda(c) and J/psi N -> (D) over bar Sigma(c), leads to a particular shape of the inelastic cross section. Analogously, we consider the mechanisms where the exchanged D collides with a nucleon and gives pi Lambda(c) or pi Sigma(c). The cross section has a peak around root s = 4415 MeV, where the J/psi N couples to a resonance predicted recently. We study the transparency ratio for electron-induced J/psi production in nuclei at about 10 GeV and find that 30-35% of the J/psi produced in heavy nuclei are absorbed inside the nucleus. This ratio is in line with depletions of J/psi through matter observed in other reactions. |
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Address |
[Molina, R.] Univ Valencia, CSIC, Ctr Mixto, Inst Invest Paterna,Dept Fis Teor, Valencia 46071, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
0556-2813 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000306191500005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1100 |
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| Permanent link to this record |
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Author |
Olmo, G.J.; Rubiera-Garcia, D. |
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Title |
Reissner-Nordstrom black holes in extended Palatini theories |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
86 |
Issue |
4 |
Pages |
044014 - 15pp |
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Keywords |
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Abstract |
We study static, spherically symmetric solutions with an electric field in an extension of general relativity containing a Ricci-squared term and formulated in the Palatini formalism. We find that all the solutions present a central core whose area is proportional to the Planck area times the number of charges. Far from the core, curvature invariants quickly tend to those of the usual Reissner-Nordstrom solution, though the structure of horizons may be different. In fact, besides the structures found in the Reissner-Nordstrom solution of general relativity, we find black hole solutions with just one nondegenerate horizon (Schwarzschild-like) and nonsingular black holes and naked cores. The charge-to-mass ratio of the nonsingular solutions implies that the core matter density is independent of the specific amounts of charge and mass and of order the Planck density. We discuss the physical implications of these results for astrophysical and microscopic black holes, construct the Penrose diagrams of some illustrative cases, and show that the maximal analytical extension of the nonsingular solutions implies a bounce of the radial coordinate. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto, CSIC, Dept Fis Teor, E-46100 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000307276200003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1114 |
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Author |
Ilisie, V.; Pich, A. |
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Title |
QCD exotics versus a standard model Higgs boson |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
86 |
Issue |
3 |
Pages |
033001 - 8pp |
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Keywords |
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Abstract |
The present collider data put severe constraints on any type of new strongly interacting particle coupling to the Higgs boson. We analyze the phenomenological limits on exotic quarks belonging to nontriplet SU(3)(C) representations and their implications on Higgs searches. The discovery of the standard model Higgs, in the experimentally allowed mass range, would exclude the presence of exotic quarks coupling to it. Thus, such QCD particles could only exist provided that their masses do not originate in the SM Higgs mechanism. |
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Address |
[Ilisie, Victor; Pich, Antonio] Univ Politecn Valencia, CSIC, IFIC, Dept Fis Teor, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000306993800004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1117 |
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| Permanent link to this record |
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Author |
Olmo, G.J.; Rubiera-Garcia, D. |
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Title |
Nonsingular black holes in quadratic Palatini gravity |
Type |
Journal Article |
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Year |
2012 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
72 |
Issue |
8 |
Pages |
2098 - 5pp |
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Keywords |
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Abstract |
We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius r(core) approximate to N(q)(1/2)l(P)/3, where l(P) is the Planck length and N-q is the number of electric charges. The singularity is avoided if the mass of the object satisfies the condition M-0(2) approximate to m(P)(2)alpha N-3/2(em)q(3)/2, where m(P) is the Planck mass and alpha(em) is the fine-structure constant. For astrophysical black holes this amount of charge is so small that their external horizon almost coincides with their Schwarzschild radius. We work within a first-order (Palatini) approach. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, Ctr Mixto, CSIC, Dept Fis Teor, E-46100 Valencia, Spain, Email: gonzalo.olmo@csic.es; |
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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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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 |
1434-6044 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000308239900030 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1138 |
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| Permanent link to this record |
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Author |
Galli, P.; Ortin, T.; Perz, J.; Shahbazi, C.S. |
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Title |
From supersymmetric to non-supersymmetric black holes |
Type |
Journal Article |
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Year |
2012 |
Publication |
Fortschritte der Physik-Progress of Physics |
Abbreviated Journal |
Fortschritte Phys.-Prog. Phys. |
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Volume |
60 |
Issue |
9-10 |
Pages |
1026-1029 |
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Keywords |
Black holes; supergravity |
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Abstract |
Methods similar to those used for obtaining supersymmetric black hole solutions can be employed to find also non-supersymmetric solutions. We briefly review some of them, with the emphasis on the non-extremal deformation ansatz of [1]. |
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Address |
[Ortin, Tomas; Perz, Jan; Shahbazi, C. S.] Inst Fis Teor UAM CSIC, Madrid 28049, Spain, Email: Pietro.Galli@ific.uv.es; |
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Thesis |
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Publisher |
Wiley-V C H Verlag Gmbh |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
0015-8208 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000308301500012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1151 |
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| Permanent link to this record |
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Author |
Olmo, G.J.; Rubiera-Garcia, D. |
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Title |
Nonsingular Charged Black Holes A La Palatini |
Type |
Journal Article |
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Year |
2012 |
Publication |
International Journal of Modern Physics D |
Abbreviated Journal |
Int. J. Mod. Phys. D |
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Volume |
21 |
Issue |
8 |
Pages |
1250067 - 6pp |
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Keywords |
Extended theories of gravity; Palatini formalism; Planck scale |
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Abstract |
We argue that the quantum nature of matter and gravity should lead to a discretization of the allowed states of the matter confined in the interior of black holes. To support and illustrate this idea, we consider a quadratic extension of general relativity (GR) formulated a la Palatini and show that nonrotating, electrically charged black holes develop a compact core at the Planck density which is nonsingular if the mass spectrum satisfies a certain discreteness condition. We also find that the area of the core is proportional to the number of charges times the Planck area. |
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Address |
[Olmo, Gonzalo J.] Univ Valencia, CSIC, Dept Fis Teor, Fac Fis, E-46100 Valencia, Spain |
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Corporate Author |
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Thesis |
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Publisher |
World Scientific Publ Co Pte Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
0218-2718 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000308497500002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1154 |
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| Permanent link to this record |
