Institute Cibernetica Matematica y Fisica ICIMAF

Havana, Cuba

Institute Cibernetica Matematica y Fisica ICIMAF

Havana, Cuba
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Cabo Montes De Oca A.,Institute Cibernetica Matematica y Fisica ICIMAF
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Second-order Newton equations of motion for a radiating particle are presented. It is argued that the trajectories obeying them also satisfy the Abraham-Lorentz-Dirac (ALD) equations for general 3D motions in the nonrelativistic and relativistic limits. The case of forces depending on only the proper time is here considered. For these properties to hold, it is sufficient that the external force be infinitely smooth and that a Landau-Lifshitz series formed with its time derivatives converges. This series defines in a special local way the effective forces entering the Newton equations. When the external force vanishes in an open vicinity of a given time, the effective one also becomes null. Thus, the proper solutions of the effective equations cannot show runaway or preacceleration effects. The Newton equations are numerically solved for a pulsed force given by an analytic function along the proper time axis. The simultaneous satisfaction of the ALD equations is numerically checked. Furthermore, a set of modified ALD equations for almost everywhere infinitely smooth forces, but including steplike discontinuities in some points, is also presented. The form of the equations supports the statement argued in a previous work, that the causal Lienard-Wiechert field solution surrounding a radiating particle implies that the effective force on the particle should instantaneously vanish when the external force is retired. The modified ALD equations proposed in the previous work are here derived in a generalized way including the same effect also when the force is instantly connected. The possibility of deriving a pointlike model showing a finite mass and an infinite electromagnetic energy from a reasonable Lagrangian theory is also started to be investigated here. © 2015 American Physical Society.


de Oca A.C.M.,Institute Cibernetica Matematica y Fisica ICIMAF
Symmetry | Year: 2010

This work expands the results and derivations presented in a recent letter. It is argued that symmetry breaking Hartree-Fock (HF) solutions of a simple model of the Cu-O planes in La 2CuO 4, are able to describe the insulator and antiferromagnetic characters of this material. Then, this classical primer of a Mott insulator is alternatively obtained here as an exact Slater insulator within the simplest of the first principles schemes. Moreover, pseudogap HF states are also predicted. The maximal energy gap of 100 meV over the Fermi surface of this wavefunction, reasonably well matches the ARPES upper pseudogap measurements for La 2CuO 4 in the zero doping limit. These surprising results followed after eliminating spin and crystal symmetry constraints usually imposed on the HF orbitals. The discussion helps to clarify the role of the antiferromagnetism and pseudogaps in the physics of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures for the description of the transition metal oxides. © 2010 by the authors.


Alvear Terrero D.,University of Habana | Castillo Garcia M.,University of Habana | Manreza Paret D.,University of Habana | Horvath J.E.,University of Sao Paulo | Perez Martinez A.,Institute Cibernetica Matematica y Fisica ICIMAF
Astronomische Nachrichten | Year: 2015

We study the anisotropic equation of state (EoS) in both strong and weak magnetic field approximations, taking into account the statistical, vacuum, and Maxwell contributions. In the strong field regime, we perform a polytropic parametrization to the anisotropic EoS, showing that the polytropic index Γ remains close to 4/3 and never reaches the value Γ = 2. We solve the Tolman-Oppenheimer-Volkoff (TOV) equations with anisotropic pressures, discarding the super-Chandrasekhar masses for magnetized white dwarfs (WD). Also, we find the solutions of the anisotropic structure equations (considering cylindrical metric), which allows us to confirm the same bound of B ∼ 1013 G from scalar virial theorem, since beyond this value there are no physical solutions. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim). Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Manreza Paret D.,University of Habana | Horvath J.H.,University of Sao Paulo | Perez Martinez A.,Institute Cibernetica Matematica y Fisica ICIMAF
Astronomische Nachrichten | Year: 2015

It is well-known that a magnetic field in a fermion system breaks the SO(3) symmetry, giving rise to an anisotropy in the energy-momentum tensor and consequently in the equation of state (EoS). Thus, the stellar structure equations of magnetized quark stars (QS) demand to be derived from a more appropriate cylindrical metric. In this work we obtain these equations considering the magnetized quark matter in two phases: Magnetized Strange Quark Matter (MSQM) and Magnetized Color Flavor Locked Phase (MCFL). The main outcome of our work is the value of the maximum magnetic field that an star can hold, i.e. 1018 G. This upper bound is closely related to the violation of the virial relations and also with the instability associated with parity-violation weak processes during the collapse of supernovae. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim). Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Tanda R.F.,Institute Cibernetica Matematica y Fisica ICIMAF | Aguado A.,Institute Cibernetica Matematica y Fisica ICIMAF
RIAI - Revista Iberoamericana de Automatica e Informatica Industrial | Year: 2013

Closed-loop identification of continuous systems, which can be considered as a nonlinear optimization problem, may result in a difficult solution problem when conventional methods are used. In this paper it is presented a hybrid strategy based on an Adaptive Genetic Algorithm and the Simplex method, that results in a satisfactory solution for this problem. The proposal is compared with other techniques reported in the literature. Three examples show the performance of the method: identification of high order dynamics; identification of unstable second order dynamics in open-loop; and parameter estimation in power generation systems. Simulation results show that the proposed is a robust method for close-loop system identification. © 2013 CEA. Publicado por Elsevier España, S. L. Todos los derechos reservados.


Cruz Rodriguez L.,University of Habana | Perez Martinez A.,Institute Cibernetica Matematica y Fisica ICIMAF | Perez Rojas H.,Institute Cibernetica Matematica y Fisica ICIMAF | Rodriguez Querts E.,Institute Cibernetica Matematica y Fisica ICIMAF
Astronomische Nachrichten | Year: 2014

The aim of this work is to study Faraday rotation in the quantum relativistic limit. Starting from the photon self-energy in the presence of a constant magnetic field the rotation of the polarization vector of a plane electromagnetic wave which travels along the fermion-antifermion gas is studied. The connection between Faraday Effect and Quantum Hall Effect (QHE) is discussed. The Faraday angle shows a resonant behavior which is related with the branching points of the Hall conductivity. Possible applications to magnetospheres of compact objects are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Perez Rojas H.,Institute Cibernetica Matematica y Fisica ICIMAF | Rodriguez Querts E.,Institute Cibernetica Matematica y Fisica ICIMAF
Astronomische Nachrichten | Year: 2014

We study the influence of a strong magnetic field on the behavior of the symmetry of an electrically neutral electroweak plasma. We analyze the case of a strong field compared with the W boson rest energy, and very low temperature. It is shown that the charged vector bosons play the most important role, leading to a modification of the symmetry breaking parameter. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Manreza Paret D.,University of Habana | Perez Martinez A.,Institute Cibernetica Matematica y Fisica ICIMAF | Ferrer E.J.,University of Texas at El Paso | de la Incera V.,University of Texas at El Paso
Astronomische Nachrichten | Year: 2014

We investigate the effects of the anomalous magnetic moment (AMM) in the EoS of a fermion system in the presence of a magnetic field. In the region of strong magnetic fields (B > m2) the AMM is found from the one-loop fermion selfenergy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field case, the AMM depends on the Landau level (LL) and decreases with it. The effects of the AMM in the EoS at intermediate-to-large fields can be found introducing the one-loop, LL-dependent AMM in the effective Lagrangian that is then used to find the thermodynamical potential of the system. We compare the plots of the parallel and perpendicular pressures versus the magnetic field in the strong field region considering the LL-dependent AMM, the Schwinger AMM, and no AMM at all. The results clearly show a separation between the physical magnitudes found using the Schwinger AMM and the LL-dependent AMM. This is an indication of the inconsistency of considering the Schwinger AMM beyond the weak field region B < m2 where it was originally found. The curves for the EoS, pressures and magnetization at different fields give rise to the well-known de Haas van Alphen oscillations, associated to the change in the number of LL contributing at different fields. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Rodriguez L.C.,University of Habana | Martinez A.P.,Institute Cibernetica Matematica y Fisica ICIMAF | Rojas H.P.,Institute Cibernetica Matematica y Fisica ICIMAF | Querts E.R.,Institute Cibernetica Matematica y Fisica ICIMAF
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We study Faraday rotation in the quantum relativistic limit. Starting from the photon self-energy in the presence of a constant magnetic field the rotation of the polarization vector of a plane electromagnetic wave which travel along the fermion-antifermion gas is studied. The connection between Faraday effect and quantum Hall effect (QHE) is discussed. The Faraday effect is also investigated for a massless relativistic (2+1)-dimensional fermion system which is derived by using the compactification along the dimension parallel to the magnetic field. The Faraday angle shows a quantized behavior as Hall conductivity in two and three dimensions. © 2013 American Physical Society.


Perez Rojas H.,Institute Cibernetica Matematica y Fisica ICIMAF | Rodriguez Querts E.,Institute Cibernetica Matematica y Fisica ICIMAF | Rodriguez Querts E.,CINVESTAV | Perez Martinez A.,Institute Cibernetica Matematica y Fisica ICIMAF
Astronomische Nachrichten | Year: 2015

We discuss the behavior of a strongly magnetized electron gas whose dominant pressure is exerted along the applied field, and extends along it as a one dimensional system. We suggest a model for maintaining the magnetic field selfconsistently, and for it we conjecture a partial bosonization of the electron gas, described by a charged vector boson field which experiences condensation, leading to a ferromagnetic behavior. Our aim is to suggest a possible quantum relativistic self-magnetized jet model. High frequency photons will be deviated also along paths parallel to the external field. Any addition of energy to the electron system, would contribute mainly to increase the kinetic energy along the magnetic field axis, an the jet may grow in this way for long times. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim). Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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