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Author Caerols, H.; Asenjo, F.A.
Title (up) Estimating the Moon-to-Earth Radius Ratio with a Smartphone, a Telescope, and an Eclipse Type
Year 2020 Publication Physics Teacher Abbreviated Journal Phys. Teach.
Volume 58 Issue 7 Pages 497-501
Keywords
Abstract From ancient times, the different features of planets and moons have created a huge interest. Aristarchus was one of the first to study the relative relations among Earth, Moon, and Sun. This interest has remained until today, and therefore it is always relevant to make this knowledge more appealing to the younger generations. Nowadays, smartphone technology has become an important tool to teach physics, and this gives us a huge opportunity to bring science closer to students in a simpler manner. In this work, we show how simple photographs of a partial lunar eclipse are sufficiently good to estimate the ratio between the Moon and Earth radii. After taking the photographs, the procedure for the calculation is straightforward and it can be reproduced easily in a one–hour class
Address [Caerols, Hugo; Asenjo, Felipe A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago, Chile, Email: felipe.asenjo@uai.cl
Corporate Author Thesis
Publisher Amer Assn Physics Teachers Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-921x ISBN Medium
Area Expedition Conference
Notes WOS:000576343700015 Approved
Call Number UAI @ alexi.delcanto @ Serial 1234
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Author Mahajan, S.M.; Asenjo, F.A.
Title (up) Explicitly covariant dispersion relations and self-induced transparency Type
Year 2017 Publication Journal Of Plasma Physics Abbreviated Journal J. Plasma Phys.
Volume 83 Issue Pages 15 pp
Keywords magnetized plasmas; plasma waves
Abstract Explicitly covariant dispersion relations for a variety of plasma waves in unmagnetized and magnetized plasmas are derived in a systematic manner from a fully covariant plasma formulation. One needs to invoke relatively little known invariant combinations constructed from the ambient electromagnetic fields and the wave vector to accomplish the program. The implication of this work applied to the self- induced transparency effect is discussed. Some problems arising from the inconsistent use of relativity are pointed out.
Address [Mahajan, S. M.] Univ Texas Austin, Inst Fus Studies, Austin, TX 78712 USA, Email: mahajan@mail.utexas.edu;
Corporate Author Thesis
Publisher Cambridge Univ Press Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3778 ISBN Medium
Area Expedition Conference
Notes WOS:000396123100018 Approved
Call Number UAI @ eduardo.moreno @ Serial 713
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Author Mahajan, S.M.; Asenjo, F.A.
Title (up) General connected and reconnected fields in plasmas Type
Year 2018 Publication Physics Of Plasmas Abbreviated Journal Phys. Plasmas
Volume 25 Issue 2 Pages 7 pp
Keywords
Abstract For plasma dynamics, more encompassing than the magnetohydrodynamical (MHD) approximation, the foundational concepts of “magnetic reconnection” may require deep revisions because, in the larger dynamics, magnetic field is no longer connected to the fluid lines; it is replaced by more general fields (one for each plasma specie) that are weighted combination of the electromagnetic and the thermal-vortical fields. We study the two-fluid plasma dynamics plasma expressed in two different sets of variables: the two-fluid (2F) description in terms of individual fluid velocities, and the one-fluid (1F) variables comprising the plasma bulk motion and plasma current. In the 2F description, a Connection Theorem is readily established; we show that, for each specie, there exists a Generalized (Magnetofluid/Electro-Vortic) field that is frozen-in the fluid and consequently remains, forever, connected to the flow. This field is an expression of the unification of the electromagnetic, and fluid forces (kinematic and thermal) for each specie. Since the magnetic field, by itself, is not connected in the first place, its reconnection is never forbidden and does not require any external agency (like resistivity). In fact, a magnetic field reconnection (local destruction) must be interpreted simply as a consequence of the preservation of the dynamical structure of the unified field. In the 1F plasma description, however, it is shown that there is no exact physically meaningful Connection Theorem; a general and exact field does not exist, which remains connected to the bulk plasma flow. It is also shown that the helicity conservation and the existence of a Connected field follow from the same dynamical structure; the dynamics must be expressible as an ideal Ohm's law with a physical velocity. This new perspective, emerging from the analysis of the post MHD physics, must force us to reexamine the meaning as well as our understanding of magnetic reconnection. Published by AIP Publishing.
Address [Mahajan, Swadesh M.] Univ Texas Austin, Inst Fus Studies, Austin, TX 78712 USA, Email: mahajan@mail.utexas.edu;
Corporate Author Thesis
Publisher Amer Inst Physics Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1070-664x ISBN Medium
Area Expedition Conference
Notes WOS:000426584700020 Approved
Call Number UAI @ eduardo.moreno @ Serial 1038
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Author Comisso, L.; Asenjo, F.A.
Title (up) Generalized magnetofluid connections in a curved spacetime Type
Year 2020 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 102 Issue 2 Pages 8 pp
Keywords
Abstract The ideal magnetohydrodynamic theorem on the conservation of the magnetic connections between plasma elements is extended to nonideal relativistic plasmas in curved spacetime. The existence of generalized magnetofluid connections that are preserved by the plasma dynamics is formalized by means of a covariant connection equation that includes different nonideal effects. These generalized connections are constituted by 2-dimensional hypersurfaces, which are linked to an antisymmetric tensor field that unifies the electromagnetic and fluid fields. They can be interpreted in terms of generalized magnetofluid vorticity field lines by considering a 3 + 1 foliation of spacetime and a time resetting projection that compensates for the loss of simultaneity between spatially separated events. The worldshects of the generalized magnetofluid vorticity field lines play a fundamental role in the plasma dynamics by prohibiting evolutions that do not preserve the magnetofluid connectivity.
Address [Comisso, Luca] Columbia Univ, Dept Astron, New York, NY 10027 USA, Email: luca.comisso@columbia.edu;
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:000552579500002 Approved
Call Number UAI @ eduardo.moreno @ Serial 1212
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Author Asenjo, F.A.; Comisso, L.; Mahajan, S.M.
Title (up) Generalized magnetofluid connections in pair plasmas Type
Year 2015 Publication Physics Of Plasmas Abbreviated Journal Phys. Plasmas
Volume 22 Issue 12 Pages 4 pp
Keywords
Abstract We extend the magnetic connection theorem of ideal magnetohydrodynamics to nonideal relativistic pair plasmas. Adopting a generalized Ohm's law, we prove the existence of generalized magnetofluid connections that are preserved by the plasma dynamics. We show that these connections are related to a general antisymmetric tensor that unifies the electromagnetic and fluid fields. The generalized magnetofluid connections set important constraints on the plasma dynamics by forbidding transitions between configurations with different magnetofluid connectivity. An approximated solution is explicitly shown where the corrections due to current inertial effects are found. (C) 2015 AIP Publishing LLC.
Address [Asenjo, Felipe A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago 7941169, Chile, Email: felipe.asenjo@uai.cl;
Corporate Author Thesis
Publisher Amer Inst Physics Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1070-664x ISBN Medium
Area Expedition Conference
Notes WOS:000367460400019 Approved
Call Number UAI @ eduardo.moreno @ Serial 573
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Author Asenjo, F.A.; Comisso, L.
Title (up) Generalized Magnetofluid Connections in Relativistic Magnetohydrodynamics Type
Year 2015 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.
Volume 114 Issue 11 Pages 5 pp
Keywords
Abstract The concept of magnetic connections is extended to nonideal relativistic magnetohydrodynamical plasmas. Adopting a general set of equations for relativistic magnetohydrodynamics including thermal-inertial, thermal electromotive, Hall, and current-inertia effects, we derive a new covariant connection equation showing the existence of generalized magnetofluid connections that are preserved during the dissipationless plasma dynamics. These connections are intimately linked to a general antisymmetric tensor that unifies the electromagnetic and fluid fields, allowing the extension of the magnetic connection notion to a much broader concept.
Address [Asenjo, Felipe A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago 7941169, Chile, Email: felipe.asenjo@uai.cl;
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 WOS:000351507400011 Approved
Call Number UAI @ eduardo.moreno @ Serial 478
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Author Asenjo, F.A.; Comisso, L.
Title (up) Gravitational electromotive force in magnetic reconnection around Schwarzschild black holes Type
Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 99 Issue 6 Pages 7 pp
Keywords
Abstract We analytically explore the effects of the gravitational electromotive force on magnetic reconnection around Schwarzschild black holes through a generalized general-relativistic magnetohydrodynamic model that retains two-fluid effects. It is shown that the gravitational electromotive force can couple to collisionless two-fluid effects and drive magnetic reconnection. This is allowed by the departure from quasineutrality in curved spacetime, which is explicitly manifested as the emergence of an effective resistivity in Ohm's law. The departure from quasineutrality is owed to different gravitational pulls experienced by separate parts of the current layer. This produces an enhancement of the reconnecion rate due to purely gravitational effects.
Address [Asenjo, Felipe A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago 7941169, Chile, Email: felipe.asenjo@uai.cl;
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:000462917900001 Approved
Call Number UAI @ eduardo.moreno @ Serial 993
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Author Mahajan, S.M.; Asenjo, F.A.
Title (up) Hot Fluids and Nonlinear Quantum Mechanics Type
Year 2015 Publication International Journal Of Theoretical Physics Abbreviated Journal Int. J. Theor. Phys.
Volume 54 Issue 5 Pages 1435-1449
Keywords Nonlinear quantum mechanics; Fluids; Temperature; High energy density physics
Abstract A hot relativistic fluid is viewed as a collection of quantum objects that represent interacting elementary particles. We present a conceptual framework for deriving nonlinear equations of motion obeyed by these hypothesized objects. A uniform phenomenological prescription, to affect the quantum transition from a corresponding classical system, is invoked to derive the nonlinear Schrodinger, Klein-Gordon, and Pauli-Schrodinger and Feynman-GellMaan equations. It is expected that the emergent hypothetical nonlinear quantum mechanics would advance, in a fundamental way, both the conceptual understanding and computational abilities, particularly, in the field of extremely high energy-density physics.
Address [Mahajan, Swadesh M.] Univ Texas Austin, Inst Fus Studies, Austin, TX 78712 USA, Email: mahajan@mail.utexas.edu;
Corporate Author Thesis
Publisher Springer/Plenum Publishers Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0020-7748 ISBN Medium
Area Expedition Conference
Notes WOS:000352858600004 Approved
Call Number UAI @ eduardo.moreno @ Serial 485
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Author Mahajan, S.M.; Asenjo, F.A.
Title (up) Interacting quantum and classical waves: Resonant and non-resonant energy transfer to electrons immersed in an intense electromagnetic wave Type
Year 2022 Publication Physics Of Plasmas Abbreviated Journal Phys. Plasmas
Volume 29 Issue 2 Pages 022107
Keywords KLEIN-GORDON; DIRAC EQUATIONS; FIELD; PARTICLE; ACCELERATION
Abstract Dynamics of electrons subjected to a constant amplitude classical electromagnetic (EM) wave is investigated as a fundamental, representative problem in the physics of interacting quantum and classical waves. In the nonrelativistic regime (electrons as Schrodinger waves), the electron energy acquires a constant and a time dependent part. Driven by EM waves, both parts scale strongly with the amplitude, but we expect no resonant enhancement since the parallel electron “speed ” of nonrelativistic electrons could never match the wave phase velocity. In the relativistic regime (electron as a Klein-Gordon wave), however, a class of electron waves (with parallel speed matching the EM phase speed) are resonantly excited to extremely high energies. Such a direct resonant energy transfer from intense electromagnetic waves constitutes a mechanism that could, in principle, power the most energetic of cosmic rays (this mechanism will work on protons just as well). Some predictions of the theory will, hopefully, be tested in laboratory laser experiments. The nonrelativistic calculations will also be examined in the context of recent experiments using photon-induced near-field electron microscopy in detail.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1070-664X ISBN Medium
Area Expedition Conference
Notes WOS:000760744200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1540
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Author Munoz, V.; Asenjo, F.A.; Dominguez, M.; Lopez, R.A.; Valdivia, J.A.; Vinas, A.; Hada, T.
Title (up) Large-amplitude electromagnetic waves in magnetized relativistic plasmas with temperature Type
Year 2014 Publication Nonlinear Processes In Geophysics Abbreviated Journal Nonlinear Process Geophys.
Volume 21 Issue 1 Pages 217-236
Keywords
Abstract Propagation of large-amplitude waves in plasmas is subject to several sources of nonlinearity due to relativistic effects, either when particle quiver velocities in the wave field are large, or when thermal velocities are large due to relativistic temperatures. Wave propagation in these conditions has been studied for decades, due to its interest in several contexts such as pulsar emission models, laser-plasma interaction, and extragalactic jets. For large-amplitude circularly polarized waves propagating along a constant magnetic field, an exact solution of the fluid equations can be found for relativistic temperatures. Relativistic thermal effects produce: (a) a decrease in the effective plasma frequency (thus, waves in the electromagnetic branch can propagate for lower frequencies than in the cold case); and (b) a decrease in the upper frequency cutoff for the Alfven branch (thus, Alfven waves are confined to a frequency range that is narrower than in the cold case). It is also found that the Alfven speed decreases with temperature, being zero for infinite temperature. We have also studied the same system, but based on the relativistic Vlasov equation, to include thermal effects along the direction of propagation. It turns out that kinetic and fluid results are qualitatively consistent, with several quantitative differences. Regarding the electromagnetic branch, the effective plasma frequency is always larger in the kinetic model. Thus, kinetic effects reduce the transparency of the plasma. As to the Alfven branch, there is a critical, nonzero value of the temperature at which the Alfven speed is zero. For temperatures above this critical value, the Alfven branch is suppressed; however, if the background magnetic field increases, then Alfven waves can propagate for larger temperatures. There are at least two ways in which the above results can be improved. First, nonlinear decays of the electromagnetic wave have been neglected; second, the kinetic treatment considers thermal effects only along the direction of propagation. We have approached the first subject by studying the parametric decays of the exact wave solution found in the context of fluid theory. The dispersion relation of the decays has been solved, showing several resonant and nonresonant instabilities whose dependence on the wave amplitude and plasma temperature has been studied systematically. Regarding the second subject, we are currently performing numerical 1-D particle in cell simulations, a work that is still in progress, although preliminary results are consistent with the analytical ones.
Address [Munoz, V.; Dominguez, M.; Lopez, R. A.; Valdivia, J. A.] Univ Chile, Fac Ciencias, Dept Fis, Santiago, Chile, Email: vmunoz@fisica.ciencias.uchile.cl
Corporate Author Thesis
Publisher Copernicus Gesellschaft Mbh Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1023-5809 ISBN Medium
Area Expedition Conference
Notes WOS:000332337700017 Approved
Call Number UAI @ eduardo.moreno @ Serial 360
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Author Asenjo, F.A.; Hojman, S.A.
Title (up) Light-like propagation of self-interacting Klein-Gordon fields in cosmology Type
Year 2022 Publication European Physical Journal Plus Abbreviated Journal Eur. Phys. J. Plus.
Volume 137 Issue 1 Pages 20
Keywords
Abstract It is showed that complex scalar fields with a self-interaction potential may propagate along null geodesics on isotropic flat Friedmann-Lemaitre-Robertson-Walker universes with different time-dependent scale factors. This effect appears for certain kinds of self-interactions only, for different forms of potentials, and even for the massive case.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-5444 ISBN Medium
Area Expedition Conference
Notes WOS:000730210100003 Approved
Call Number UAI @ alexi.delcanto @ Serial 1501
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Author Asenjo, F.A.; Comisso, L.
Title (up) Magnetic connections in curved spacetime Type
Year 2017 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 96 Issue 12 Pages 7 pp
Keywords
Abstract The ideal magnetohydrodynamic theorem on the conservation of the magnetic connections between plasma elements is generalized to relativistic plasmas in curved spacetime. The connections between plasma elements, which are established by a covariant connection equation, display a particularly complex structure in curved spacetime. Nevertheless, it is shown that these connections can be interpreted in terms of magnetic field lines alone by adopting a 3 + 1 foliation of spacetime.
Address [Asenjo, Felipe A.] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Santiago 7941169, Chile, Email: felipe.asenjo@uai.cl;
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:000417759400002 Approved
Call Number UAI @ eduardo.moreno @ Serial 785
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Author Qadir, A.; Asenjo, F.A.; Mahajan, S.M.
Title (up) Magnetic field seed generation in plasmas around charged and rotating black holes Type
Year 2014 Publication Physica Scripta Abbreviated Journal Phys. Scr.
Volume 89 Issue 8 Pages 7 pp
Keywords seed magnetic field; general relativistic drive; Kerr metric
Abstract Previous work by the authors introduced the possibility of generating seed magnetic fields by spacetime curvature and applied it in the vicinity of a Schwarzschild black hole. It was pointed out that it would be worthwhile to consider the effect in other background geometries and particularly in the vicinity of a rotating black hole, which is generically to be expected, astrophysically. In this paper that suggestion is followed up and we calculate generated magnetic field seed due to Reissner-Nordstrom and Kerr spacetimes. The conditions for the drive for the seed of a magnetic field is obtained for charged black holes, finding that in the horizon the drive vanishes. Also, the psi N-force produced by the Kerr black hole is obtained and its relation with the magnetic field seed is discussed, producing a more effective drive.
Address [Qadir, Asghar] Natl Univ Sci & Technol, Ctr Adv Math & Phys, Islamabad 4400, Pakistan, Email: aqadirmath@yahoo.com
Corporate Author Thesis
Publisher Iop Publishing Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-8949 ISBN Medium
Area Expedition Conference
Notes WOS:000343295000004 Approved
Call Number UAI @ eduardo.moreno @ Serial 469
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Author Comisso, L.; Asenjo, F.A.
Title (up) Magnetic reconnection as a mechanism for energy extraction from rotating black holes Type
Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D.
Volume 103 Issue 2 Pages 023014
Keywords BLANDFORD-ZNAJEK MECHANISM; NEAR-INFRARED FLARES; SIMULATIONS; JETS; DRIVEN
Abstract Spinning black holes store rotational energy that can be extracted. When a black hole is immersed in an externally supplied magnetic field, reconnection of magnetic field lines within the ergosphere can generate negative energy (relative to infinity) particles that fall into the black hole event horizon while the other accelerated particles escape stealing energy from the black hole. We show analytically that energy extraction via magnetic reconnection is possible when the black hole spin is high (dimensionless spin a similar to 1) and the plasma is strongly magnetized (plasma magnetization sigma(0) > 1/3). The parameter space region where energy extraction is allowed depends on the plasma magnetization and the orientation of the reconnecting magnetic field lines. For sigma(0) >> 1, the asymptotic negative energy at infinity per enthalpy of the decelerated plasma that is swallowed by a maximally rotating black hole is found to be epsilon(infinity)(-) similar or equal to – root sigma(0)/3. The accelerated plasma that escapes to infinity and takes away black hole energy asymptotes the energy at infinity per enthalpy epsilon(infinity)(+) similar or equal to root 3 sigma(0).. We show that the maximum power extracted from the black hole by the escaping plasma is P-extr(max) similar to 0.1M(2) root sigma(0)w(0) (here, M is the black hole mass and w(0) is the plasma enthalpy density) for the collisionless plasma regime and one order of magnitude lower for the collisional regime. Energy extraction causes a significant spindown of the black hole when a similar to 1. The maximum efficiency of the plasma energization process via magnetic reconnection in the ergosphere is found to be eta(max) similar or equal to 3/2. Since fast magnetic reconnection in the ergosphere should occur intermittently in the scenario proposed here, the associated emission within a few gravitational radii from the black hole is expected to display a bursty nature.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language 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:000607513600001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1323
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Author Asenjo, F.A.; Hojman, S.A.
Title (up) New non-linear modified massless Klein-Gordon equation Type
Year 2017 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 77 Issue 11 Pages 5 pp
Keywords
Abstract The massless Klein-Gordon equation on arbitrary curved backgrounds allows for solutions which develop “tails” inside the light cone and, therefore, do not strictly follow null geodesics as discovered by DeWitt and Brehme almost 60 years ago. A modification of the massless Klein-Gordon equation is presented, which always exhibits null geodesic propagation of waves on arbitrary curved space-times. This new equation is derived from a Lagrangian which exhibits current-current interaction. Its non-linearity is due to a self-coupling term which is related to the quantum mechanical Bohm potential.
Address [Asenjo, Felipe A.; Hojman, Sergio A.] Univ Adolfo Ibanez, UAI Phys Ctr, Santiago, Chile, Email: felipe.asenjo@uai.cl;
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:000414439100003 Approved
Call Number UAI @ eduardo.moreno @ Serial 791
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Author Hojman, S.A.; Asenjo, F.A.
Title (up) Non-geodesic circular motion of massive spinning test bodies around a Schwarzschild field in the Lagrangian theory Type
Year 2018 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 78 Issue 10 Pages 7 pp
Keywords
Abstract Recent interest on studying possible violations of the Equivalence Principle has led to the development of space satellite missions testing it for bodies moving on circular orbits around Earth. This experiment establishes that the validity of the equivalence principle is independent of the composition of bodies. However, the internal degrees of freedom of the bodies (such as spin) were not taken into account. In this work, it is shown exactly that the circular orbit motion of test bodies does present a departure from geodesic motion when spin effects are not negligible. Using a Lagrangian theory for spinning massive bodies, an exact solution for their circular motion is found showing that the non-geodesic behavior manifests through different tangential velocities of the test bodies, depending on the orientation of its spin with respect to the total angular momentum of the satellite. Besides, for circular orbits, spinning test bodies present no tangential acceleration. We estimate the difference of the two possible tangential velocities for the case of circular motion of spinning test bodies orbiting Earth.
Address [Hojman, Sergio A.] Univ Adolfo Ibanez, Fac Artes Liberales, Dept Ciencias, Santiago, Chile, Email: sergio.hojman@uai.cl;
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:000447801100002 Approved
Call Number UAI @ eduardo.moreno @ Serial 921
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Author Asenjo, F.A.; Hojman, S.A.
Title (up) Nondiffracting gravitational waves Type
Year 2021 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 81 Issue 1 Pages 98
Keywords
Abstract It is proved that accelerating nondiffracting gravitational Airy wave-packets are solutions of linearized gravity. It is also showed that Airy functions are exact solutions to Einstein equations for non-accelerating nondiffracting gravitational wave-packets.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language 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:000616135600003 Approved
Call Number UAI @ alexi.delcanto @ Serial 1336
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Author Hojman, S.A.; Asenjo, F.A.
Title (up) Phenomenological dynamics of COVID-19 pandemic: Meta-analysis for adjustment parameters Type
Year 2020 Publication Chaos Abbreviated Journal Chaos
Volume 30 Issue 10 Pages 12 pp
Keywords
Abstract We present a phenomenological procedure of dealing with the COVID-19 (coronavirus disease 2019) data provided by government health agencies of 11 different countries. Usually, the exact or approximate solutions of susceptible-infected-recovered (or other) model(s) are obtained fitting the data by adjusting the time-independent parameters that are included in those models. Instead of that, in this work, we introduce dynamical parameters whose time-dependence may be phenomenologically obtained by adequately extrapolating a chosen subset of the daily provided data. This phenomenological approach works extremely well to properly adjust the number of infected (and removed) individuals in time for the countries we consider. Besides, it can handle the sub-epidemic events that some countries may experience. In this way, we obtain the evolution of the pandemic without using any a priori model based on differential equations.
Address [Hojman, Sergio A.] Univ Adolfo Ibanez, Fac Artes Lib, Dept Ciencias, Santiago 7491169, Chile, Email: sergio.hojman@uai.cl;
Corporate Author Thesis
Publisher Amer Inst Physics Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1054-1500 ISBN Medium
Area Expedition Conference
Notes WOS:000585761000001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1257
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Author Asenjo, F.A.; Hojman, S.A.; Moya-Cessa, H.M.; Soto-Eguibar, F.
Title (up) Propagation of light in linear and quadratic GRIN media: The Bohm potential Type
Year 2021 Publication Optics Communications Abbreviated Journal Opt. Commun.
Volume 490 Issue Pages 126947
Keywords
Abstract It is shown that field propagation in linear and quadratic gradient-index (GRIN) media obeys the same rules of free propagation in the sense that a field propagating in free space has a (mathematical) form that may be exported to those particular GRIN media. The Bohm potential is introduced in order to explain the reason of such behavior: it changes the dynamics by modifying the original potential . The concrete cases of two different initials conditions for each potential are analyzed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0030-4018 ISBN Medium
Area Expedition Conference
Notes WOS:000664742700011 Approved
Call Number UAI @ alexi.delcanto @ Serial 1424
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Author Rubio, C.A.; Asenjo, F.A.; Hojman, S.A.
Title (up) Quantum Cosmologies Under Geometrical Unification of Gravity and Dark Energy Type
Year 2019 Publication Symmetry-Basel Abbreviated Journal Symmetry
Volume 11 Issue 7 Pages
Keywords
Abstract A Friedmann-Robertson-Walker Universe was studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann-Robertson-Walker-quintessence (FRWq) system, was presented. It was shown that the classical Lagrangian reproduces the usual two (second order) dynamical equations for the radius of the Universe and for the quintessence scalar field, as well as a (first order) constraint equation. Our approach naturally unified gravity and dark energy, as it was obtained that the Lagrangian and the equations of motion are those of a relativistic particle moving on a two-dimensional, conformally flat spacetime. The conformal metric factor was related to the dark energy scalar field potential. We proceeded to quantize the system in three different schemes. First, we assumed the Universe was a spinless particle (as it is common in literature), obtaining a quantum theory for a Universe described by the Klein-Gordon equation. Second, we pushed the quantization scheme further, assuming the Universe as a Dirac particle, and therefore constructing its corresponding Dirac and Majorana theories. With the different theories, we calculated the expected values for the scale factor of the Universe. They depend on the type of quantization scheme used. The differences between the Dirac and Majorana schemes are highlighted here. The implications of the different quantization procedures are discussed. Finally, the possible consequences for a multiverse theory of the Dirac and Majorana quantized Universe are briefly considered.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2073-8994 ISBN Medium
Area Expedition Conference
Notes WOS:000481979000025 Approved
Call Number UAI @ eduardo.moreno @ Serial 1048
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