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Search Results: 1 - 10 of 401188 matches for " M. Moshinsky "
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Alternative method for determining the Feynman propagator of a relativistic quantum mechanical problem
Moshinsky, M;Sadurní, E;
Revista mexicana de física , 2008,
Abstract: the authors, together with a. del campo, developed an alternative method for determining the feynman propagator [1] for a non-relativistic problem. one started with the time dependent schroedinger equation for the problem. carried out a laplace transform with respect to time to get the equation for the energy dependent green function and derived it explicitly. we then carried out the inverse laplace transform in the energy to get feynman propagator. in this paper we carry out the same programme for a relativistic problem associated with the one dimensional dirac equation of a free particle and the dirac oscillator proposed by moshinsky and szczepaniak [2] twenty years ago.
Time dependent problems in relativistic quantum mechanics
Moshinsky, M.;Sadurní, E.;
Revista mexicana de física , 2006,
Abstract: the most effective procedure for dealing with time dependent problems is through the feynman propagator. in this note we indicate the explicit expression for this propagator in relativistic problems using spectral decomposition. we then take as an initial state one of a dirac oscillator and consider the behaviour of the wave function when the interaction is suddenly supressed.
Transition from quantum to classical behavior for some simple model systems
D. Schuch,M. Moshinsky
Revista mexicana de física , 2005,
Abstract: There is an increasing interest in the question of why typical quantum mechanical properties, such as those connected with the superposition of states or diffraction patterns for material systems, are not observed on the classical macroscopic level. By discussing two simple model problems connected via the free-particle propagator, we show under what circumstances typical quantum effects that show up in these systems can attain significant magnitudes so as to have a chance to be observable. The influence of the interaction with a dissipative environment will also be considered, and the time scale where the effects reach their maximum and how they decay afterwards will be discussed. Furthermore, a comparison with recent scattering experiments will be given.
Time dependent problems in relativistic quantum mechanics
M. Moshinsky,E. Sadurní
Revista mexicana de física , 2006,
Abstract: La manera más efectiva para analizar problemas dependientes del tiempo en mecánica cuántica es a través del propagador de Feynman. En esta nota indicamos la forma explícita de este propagador en problemas relativistas, usando la decomposición espectral. Posteriormente tomamos un estado del oscilador de Dirac como condición inicial y estudiamos el comportamiento de la función de onda cuando la interacción desaperece repentinamente.
Alternative method for determining the Feynman propagator of a relativistic quantum mechanical problem
M. Moshinsky,E. Sadurní
Revista mexicana de física , 2008,
Abstract: Los autores desarrollaron, junto con A. del Campo, un método alternativo para determinar el propagador de Feynman para un problema norelativista. El método consiste en la evaluación de la transformada de Laplace con respecto al tiempo para derivar la ecuación para la función de Green dependiente de energía. Se obtiene el propagador de Feynman usando la transformada inversa de Laplace de la función de Green. En este artículo llevamos a cabo el mismo programa para un problema relativista asociado a la ecuación de Dirac en una dimensión de una partícula libre y el oscilador de Dirac propuesto hace veinte anos por Moshinsky and Szczepaniak [2].
Baryons in O(4) and Vibron Model
M. Kirchbach,M. Moshinsky,Yu. F. Smirnov
Physics , 2001, DOI: 10.1103/PhysRevD.64.114005
Abstract: The structure of the reported excitation spectra of the light unflavored baryons is described in terms of multi-spin valued Lorentz group representations of the so called Rarita-Schwinger (RS) type (K/2, K/2)* [(1/ 2,0)+ (0,1/2)] with K=1,3, and 5. We first motivate legitimacy of such pattern as fundamental fields as they emerge in the decomposition of triple fermion constructs into Lorentz representations. We then study the baryon realization of RS fields as composite systems by means of the quark version of the U(4) symmetric diatomic rovibron model. In using the U(4)/ O(4)/ O(3)/ O(2) reduction chain, we are able to reproduce quantum numbers and mass splittings of the above resonance assemblies. We present the essentials of the four dimensional angular momentum algebra and construct electromagnetic tensor operators. The predictive power of the model is illustrated by ratios of reduced probabilities concerning electric de-excitations of various resonances to the nucleon.
Transient phenomena in quantum mechanics
Godoy, S;Kramer, T;Moshinsky, M;
Revista mexicana de física , 2006,
Abstract: transient phenomena in quantum mechanics imply solving the time dependent schrodinger equation with appropriate initial and boundary conditions. in this paper we consider the general formulation of the one dimensional problem and apply it to the particular example of transient phenomena for the bound state of a delta potential perturbed by the action of a boundary condition.
Transient phenomena in quantum mechanics
S. Godoy,T. Kramer,M. Moshinsky
Revista mexicana de física , 2006,
Abstract: Fenómenos transitorios en mecánica cuántica implican resolver la ecuación de Schrodinger dependiente del tiempo con condiciones iniciales y de frontera. En este trabajo consideramos la formulación general del problema unidimensional y la aplicamos al ejemplo particular del fenómeno transitorio para el estado ligado de un potencial delta, perturbado por la acción de una condición a la frontera.
Supersymmetry and superalgebra for the two-body system with a Dirac oscillator interaction
M. Moshinsky,C. Quesne,Yu. F. Smirnov
Physics , 1995, DOI: 10.1088/0305-4470/28/22/020
Abstract: Some years ago, one of the authors~(MM) revived a concept to which he gave the name of single-particle Dirac oscillator, while another~(CQ) showed that it corresponds to a realization of supersymmetric quantum mechanics. The Dirac oscillator in its one- and many-body versions has had a great number of applications. Recently, it included the analytic expression for the eigenstates and eigenvalues of a two-particle system with a new type of Dirac oscillator interaction of frequency~$\omega$. By considering the latter together with its partner corresponding to the replacement of~$\omega$ by~$-\omega$, we are able to get a supersymmetric formulation of the problem and find the superalgebra that explains its degeneracy.
Survival and Nonescape Probabilities for Resonant and Nonresonant Decay
G. Garcia-Calderon,J. L. Mateos,M. Moshinsky
Physics , 1996, DOI: 10.1006/aphy.1996.0078
Abstract: In this paper we study the time evolution of the decay process for a particle confined initially in a finite region of space, extending our analysis given recently (Phys. Rev. Lett. 74, 337 (1995)). For this purpose, we solve exactly the time-dependent Schroedinger equation for a finite-range potential. We calculate and compare two quantities: (i) the survival probability S(t), i.e., the probability that the particle is in the initial state after a time t; and (ii) the nonescape probability P(t), i.e., the probability that the particle remains confined inside the potential region after a time t. We analyze in detail the resonant and nonresonant decay. In the former case, after a very short time, S(t) and P(t) decay exponentially, but for very long times they decay as a power law, albeit with different exponents. For the nonresonant case we obtain that both quantities differ initially. However, independently of the resonant and nonresonant character of the initial state we always find a transition to the ground state of the system which indicates a process of ``loss of memory'' in the decay.
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