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Author |
Lobo, F.S.N.; Olmo, G.J.; Orazi, E.; Rubiera-Garcia, D.; Rustam, A. |
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Title |
Structure and stability of traversable thin-shell wormholes in Palatini f(R) gravity |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
102 |
Issue |
10 |
Pages |
104012 - 11pp |
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Keywords |
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Abstract |
We study the structure and stability of traversable wormholes built as (spherically symmetric) thin shells in the context of Palatini f(R) gravity. Using a suitable junction formalism for these theories we find that the effective number of degrees of freedom on the shell is reduced to a single one, which fixes the equation of state to be that of massless stress-energy fields, contrary to the general relativistic and metric f(R) cases. Another major difference is that the surface energy density threading the thin shell, needed in order to sustain the wormhole, can take any sign and may even vanish, depending on the desired features of the corresponding solutions. We illustrate our results by constructing thin-shell wormholes by surgically grafting Schwarzschild space-times and show that these configurations are always linearly unstable. However, surgically joined Reissner-Nordstrom space-times allow for linearly stable, traversable thin-shell wormholes supported by a positive energy density provided that the (squared) mass-to-charge ratio, given by y = Q(2)/M-2, satisfies the constraint 1 < y < 9/8 (corresponding to overcharged Reissner-Nordstrom configurations having a photon sphere) and lies in a region bounded by specific curves defined in terms of the (dimensionless) radius of the shell x(0) = R/M. |
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Address |
[Lobo, Francisco S. N.] Univ Lisbon, Fac Ciencias, Inst Astrofis & Ciencias Espaco, Edificio C8,Campo Grande, P-1749016 Lisbon, Portugal, Email: fslobo@fc.ul.pt; |
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Thesis |
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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 |
2470-0010 |
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Expedition |
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Conference |
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Notes |
WOS:000587286200006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4596 |
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Permanent link to this record |
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Author |
Blas, D.; Witte, S.J. |
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Title |
Quenching mechanisms of photon superradiance |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
102 |
Issue |
12 |
Pages |
123018 - 10pp |
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Keywords |
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Abstract |
Rapidly rotating black holes are known to develop instabilities in the presence of a sufficiently light boson, a process which becomes efficient when the boson's Compton wavelength is roughly the size of the black hole. This phenomenon known as black hole superradiance generates an exponentially growing boson cloud at the expense of the rotational energy of the black hole. For astrophysical black holes with M similar to O(10)M-circle dot, the superradiant condition is achieved for bosons with m(b) similar to O(10(-11))eV; intriguingly, photons traversing the intergalactic medium acquire an effective mass (due to their interactions with the ambient plasma) which naturally resides in this range. The implications of photon superradiance, i.e., the evolution of the superradiant photon cloud and ambient plasma in the presence of scattering and particle production processes, have yet to be thoroughly investigated. Here, we enumerate and discuss a number of different processes capable of quenching the growth of the photon cloud, including particle interactions with the ambient electrons and backreactions on the effective mass (arising e.g., from thermal effects, pair production, ionization of the local background, and modifications to the dispersion relation from strong electric fields). This work naturally serves as a guide in understanding how interactions may allow light exotic bosons to evade superradiant constraints. |
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Address |
[Blas, Diego] Kings Coll London, Dept Phys, Theoret Particle Phys & Cosmol Grp, London WC2R 2LS, England, Email: diego.blas@kcl.ac.uk; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
2470-0010 |
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:000599093100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4666 |
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Permanent link to this record |
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Author |
Blas, D.; Witte, S.J. |
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Title |
Imprints of axion superradiance in the CMB |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
102 |
Issue |
10 |
Pages |
103018 - 10pp |
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Keywords |
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Abstract |
Light axions (m(a) less than or similar to 10(-10) eV) can form dense clouds around rapidly rotating astrophysical black holes via a mechanism known as rotational superradiance. The coupling between axions and photons induces a parametric resonance, arising from the stimulated decay of the axion cloud, which can rapidly convert regions of large axion number densities into an enormous flux of low-energy photons. In this work we consider the phenomenological implications of a superradiant axion cloud undergoing resonant decay. We show that the low-energy photons produced from such events will be absorbed over cosmologically short distances, potentially inducing massive shockwaves that heat and ionize the intergalactic medium over Mpc scales. These shockwaves may leave observable imprints in the form of anisotropic spectral distortions or inhomogeneous features in the optical depth. |
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Address |
[Blas, Diego] Kings Coll London, Dept Phys, Theoret Particle Phys & Cosmol Grp, London WC2R 2LS, England, Email: diego.blas@kcl.ac.uk; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
2470-0010 |
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:000589606900004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4609 |
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Permanent link to this record |
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Author |
Anderson, P.R.; Siahmazgi, S.G.; Clark, R.D.; Fabbri, A. |
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Title |
Method to compute the stress-energy tensor for a quantized scalar field when a black hole forms from the collapse of a null shell |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
102 |
Issue |
12 |
Pages |
125035 - 26pp |
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Keywords |
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Abstract |
A method is given to compute the stress-energy tensor for a massless minimally coupled scalar field in a spacetime where a black hole forms from the collapse of a spherically symmetric null shell in four dimensions. Part of the method involves matching the modes for the in vacuum state to a complete set of modes in Schwarzschild spacetime. The other part involves subtracting from the unrenormalized expression for the stress-energy tensor when the field is in the in vacuum state, the corresponding expression when the field is in the Unruh state and adding to this the renormalized stress-energy tensor for the field in the Unruh state. The method is shown to work in the two-dimensional case where the results are known. |
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Address |
[Anderson, Paul R.; Siahmazgi, Shohreh Gholizadeh; Clark, Raymond D.] Wake Forest Univ, Dept Phys, Winston Salem, NC 27109 USA, Email: anderson@wfu.edu; |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
Spanish |
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 |
2470-0010 |
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:000604246500005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4673 |
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Permanent link to this record |
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Author |
Poley, L. et al; Bernabeu, J.; Civera, J.V.; Lacasta, C.; Leon, P.; Platero, A.; Platero, V; Solaz, C.; Soldevila, U.; Vidal, G. |
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Title |
The ABC130 barrel module prototyping programme for the ATLAS strip tracker |
Type |
Journal Article |
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Year |
2020 |
Publication |
Journal of Instrumentation |
Abbreviated Journal |
J. Instrum. |
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Volume |
15 |
Issue |
9 |
Pages |
P09004 - 78pp |
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Keywords |
Detector design and construction technologies and materials; Si microstrip and pad detectors; Radiation-hard detectors; Front-end electronics for detector readout |
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Abstract |
For the Phase-II Upgrade of the ATLAS Detector [1], its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100% silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-250) [2, 3] and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests. |
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Address |
[Poley, L.; Anderssen, E.; Ciocio, A.; Cornell, E.; Haber, C.; Haugen, T. E.; Heim, T.; Johnson, T. A.; Krizka, K.; Labitan, C.; Li, B.; Li, C.; MacFadyen, R.; Mladina, E.; Ottino, G.; Sanethavong, P.; Santpur, S. Neha; Witharm, R.] Lawrence Berkeley Natl Lab, Cyclotron Rd, Berkeley, CA 94720 USA, Email: APoley@cern.ch |
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Corporate Author |
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Thesis |
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Publisher |
Iop Publishing 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 |
1748-0221 |
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:000577273400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4572 |
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Permanent link to this record |