Non-linear generalization of the sl(2) algebra

We present a generalization of the sl(2) algebra where the algebraic relations are constructed with the help of a general function of one of the generators. When this function is linear this algebra is a deformed sl(2) algebra. In the non-linear case, the finite dimensional representations are constructed in two different ways. In the first case, which provides finite dimensional representations only for the non-linear case, these representations come from solutions to a dynamical equation and we show how to construct explicitly these representations for a general quadratic non-linear function. The other type of finite dimensional representation comes from solutions to a cut condition equation. We give examples of solutions of this type in the non-linear case as well.Comment: 13 pages, 3 EPS figures, Late

Gravity and Geometric Phases

The behavior of a quantum test particle satisfying the Klein-Gordon equation in a certain class of 4 dimensional stationary space-times is examined. In a space-time of a spinning cosmic string, the wave function of a particle in a box is shown to acquire a geometric phase when the box is transported around a closed path surrounding the string. When interpreted as an Aharonov-Anandan geometric phase, the effect is shown to be related to the Aharonov-Bohm effect.Comment: 11 pages, latex fil

Generalized quantum field theory: perturbative computation and perspectives

We analyze some consequences of two possible interpretations of the action of the ladder operators emerging from generalized Heisenberg algebras in the framework of the second quantized formalism. Within the first interpretation we construct a quantum field theory that creates at any space-time point particles described by a q-deformed Heisenberg algebra and we compute the propagator and a specific first order scattering process. Concerning the second one, we draw attention to the possibility of constructing this theory where each state of a generalized Heisenberg algebra is interpreted as a particle with different mass.Comment: 19 page

Clinical outcomes of patients with acute myeloid leukemia: evaluation of genetic and molecular findings in a real-life setting

sem informação1261518631865sem informaçãosem informaçã

Theoretical investigation of the 7F1 level splitting in a series of Eu3+ doped oxides matrixes

The point charge electrostatic model (PCEM) and the simple overlap model (SOM) are applied to a series of oxide crystals (Gd2O3, Y2O3, Lu2O3, In2O3 and Sc2O3) and a silicate glass (Al2O3–SiO2) doped with the Eu3+ ion. The SOM factor ρ(2β)k+1 is input as the shielding factor for all B q k expressions, which enters in the calculations of the crystal-field strength parameter, NV. The maximum splitting ΔE of the 7F1 manifold of the Eu3+ ion is then obtained as a function of NV. It has been developed another way to calculate alpha, which is an expansion factor in the ΔE expression. For the glass, as the mean metal-ligating ions distances are larger than for the crystals, NV and ΔE are smaller, as expected. The prediction of the PCEM shows a linear dependence between ΔE and NV, even though the known mismatch in respect to the experimental splitting is kept. In the case of the SOM, two situations have been analyzed: firstly the charge factor varies in order to reproduce the experimental splitting (a phenomenological procedure); secondly the charge factor is the valence of the oxygen ions. The agreement between the experimental results and theoretical predictions for all investigated systems is very satisfactory in respect to both the linearity between ΔE and NV and the ΔE splitting

Wakes in Dilatonic Current-Carrying Cosmic Strings

In this work, we present the gravitational field generated by a cosmic string carrying a timelike current in the scalar-tensor gravities. The mechanism of formation and evolution of wakes is fully investigated in this framework. We show explicitly that the inclusion of electromagnetic properties for the string induces logarithmic divergences in the accretion problem.Comment: Revised version to be published in the Phys. Rev.

Thermal correction to the Casimir force, radiative heat transfer, and an experiment

The low-temperature asymptotic expressions for the Casimir interaction between two real metals described by Leontovich surface impedance are obtained in the framework of thermal quantum field theory. It is shown that the Casimir entropy computed using the impedance of infrared optics vanishes in the limit of zero temperature. By contrast, the Casimir entropy computed using the impedance of the Drude model attains at zero temperature a positive value which depends on the parameters of a system, i.e., the Nernst heat theorem is violated. Thus, the impedance of infrared optics withstands the thermodynamic test, whereas the impedance of the Drude model does not. We also perform a phenomenological analysis of the thermal Casimir force and of the radiative heat transfer through a vacuum gap between real metal plates. The characterization of a metal by means of the Leontovich impedance of the Drude model is shown to be inconsistent with experiment at separations of a few hundred nanometers. A modification of the impedance of infrared optics is suggested taking into account relaxation processes. The power of radiative heat transfer predicted from this impedance is several times less than previous predictions due to different contributions from the transverse electric evanescent waves. The physical meaning of low frequencies in the Lifshitz formula is discussed. It is concluded that new measurements of radiative heat transfer are required to find out the adequate description of a metal in the theory of electromagnetic fluctuations.Comment: 19 pages, 4 figures. svjour.cls is used, to appear in Eur. Phys. J.

Static And Dynamic Properties Of Fibonacci Multilayers

We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures. © 2013 American Institute of Physics.11317Grünberg, P., Schreiber, R., Pang, Y., Brodsky, M.B., Sowers, H., (1986) Phys. Rev. Lett., 57, p. 2442. , 10.1103/PhysRevLett.57.2442Baibich, M.N., Broto, J.M., Fert, A., Nguyen Van Dau, F., Petroff, F., Etienne, P., Creuzet, G., Chazelas, J., (1988) Phys. Rev. Lett., 61, p. 2472. , 10.1103/PhysRevLett.61.2472Binasch, G., Grünberg, P., Saurenbach, F., Zinn, W., (1989) Phys. Rev. B, 39, p. 4828. , 10.1103/PhysRevB.39.4828Prinz, G.A., (1998) Science, 282, p. 1660. , 10.1126/science.282.5394.1660Kools, J.C.S., (1996) IEEE Trans. Magn., 32, p. 3165. , 10.1109/20.508381Stiles, M.D., Zangwill, A., (2002) Phys. Rev. B, 66, p. 014407. , 10.1103/PhysRevB.66.014407Lakys, Y., Zhao, W.S., Devolder, T., Zhang, Y., Klein, J.O., Ravelosona, D., Chappert, C., (2012) IEEE Trans. Magn., 48, p. 2403. , 10.1109/TMAG.2012.2194790Chaves, R.C., Cardoso, S., Ferreira, R., Freitas, P.P., (2011) J. Appl. Phys, 109, pp. 07E506. , 10.1063/1.3537926Vedyayev, A., Dieny, B., Ryzhanova, N., Genin, J.B., Cowache, C., (1994) Europhys. Lett., 25, p. 465. , 10.1209/0295-5075/25/6/012Albuquerque, E.L., Cottam, M.G., (2004) Polaritons in Periodic and Quasiperiodic Structures, , (Elsevier, Amsterdam)Bezerra, C.G., Albuquerque, E.L., (1997) Physica A, 245, p. 379. , 10.1016/S0378-4371(97)00309-9Bezerra, C.G., De Araujo, J.M., Chesman, C., Albuquerque, E.L., (1999) Phys. Rev. B, 60, p. 9264. , 10.1103/PhysRevB.60.9264Bezerra, C.G., De Araujo, J.M., Chesman, C., Albuquerque, E.L., (2001) J. Appl. Phys., 89, p. 2286. , 10.1063/1.1340600Bezerra, C.G., Cottam, M.G., (2002) J. Magn. Magn. Mater., 240, p. 529. , 10.1016/S0304-8853(01)00838-1Bezerra, C.G., Cottam, M.G., (2002) Phys. Rev. B, 65, p. 054412. , 10.1103/PhysRevB.65.054412Mauriz, P.W., Albuquerque, E.L., Bezerra, C.G., (2002) J. Phys.: Condens. Matter, 14, p. 1785. , 10.1088/0953-8984/14/8/308Fullerton, E.E., Conover, M.J., Mattson, J.E., Sowers, C.H., Bader, S.D., (1993) Phys. Rev. B, 48, p. 15755. , 10.1103/PhysRevB.48.15755Machado, L.D., Bezerra, C.G., Correa, M.A., Chesman, C., Pearson, J.E., Hoffmann, A., (2012) Phys. Rev. B, 85, p. 224416. , 10.1103/PhysRevB.85.22441

On the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects on the Harmonic Oscillator

In this work, we obtain bound states for a nonrelativistic spin-half neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present a new possible scenario of studying the Lorentz symmetry breaking effects on a nonrelativistic quantum system defined by a fixed space-like vector field parallel to the radial direction interacting with a uniform magnetic field along the z-axis. Furthermore, we also discuss the influence of a Coulomb-like potential induced by Lorentz symmetry violation effects on the two-dimensional harmonic oscillator.Comment: 14 pages, no figure, this work has been accepted for publication in The European Physical Journal Plu