Dissipation-assisted tunneling in asymmetric double-well potentials

1995 ◽  
Vol 73 (3-4) ◽  
pp. 131-137 ◽  
Author(s):  
M. Razavy

The motion of the center of a wave packet localized in one of the wells of an asymmetric double-well potential is studied. The asymmetric potential is obtained from a solvable symmetric potential using the Gel'fand–Levitan formalism, by keeping the energy eigenvalues unchanged, but changing the normalization of the ground-state wave function. While in a symmetric double well the wave packet tunnels back and forth between the two wells, for an asymmetric well, in general, tunneling does not take place. This is independent of the initial location of the wave packet, i.e., whether it is centered at the minimum of the shallower or of the deeper well. However, when such a system is coupled to a dissipative force, then the tunneling becomes possible. For instance it is shown that if, as a model of dissipative coupling, one chooses Gisin's nonlinear evolution equation, then the center of the wave packet ends up in the deeper well (decay of false vacuum). This result depends on the particular model of dissipation, for instance, an optical potential model yields a different result.

2002 ◽  
Vol 11 (05) ◽  
pp. 425-436 ◽  
Author(s):  
M. Y. H. FARAG ◽  
M. Y. M. HASSAN

The relativistic description of the proton-nucleus elastic scattering can be considered within the framework of a relativistic optical potential model. The elastic scattering of proton with the nuclei 12 C , 16 O , 20 Ne , and 24 Mg at 800 MeV and 1.04 GeV are studied for relativistic and nonrelativistic treatments. The real optical potentials and the differential cross sections of these reactions are calculated. The obtained results are compared with the corresponding results obtained from the calculation depending on the Woods–Saxon optical potential which were adjusted to fit the experimental data. The present results are in good agreement with the experimental data.


2015 ◽  
Vol 1084 ◽  
pp. 200-204
Author(s):  
Vladimir A. Tryasuchev ◽  
Andrey V. Isaev

Necessary conditions of quasi-bound state formation of η-meson with isotopes3He,4He have been found within the framework of optical potential model. These conditions have been compared with the findings about helium nucleus densities and with the available information about ηN-scattering length. Thus, we have concluded that within the framework of discussed model η−3He quasi-bound state formation is not possible, but η−4He quasi-bound state formation is possible with great probability.


1991 ◽  
Vol 44 (3) ◽  
pp. 265 ◽  
Author(s):  
K Ratnavelu

The continuum optical potential model is used to calculate the ionisation cross sections of H and He by positron impact. The present e+-H result is compared with the recent first measurement of e+ -H ionisation cross sections. The e+ -He calculation is also presented, together with the experimental measurements. A comparison with other theoretical results is also given.


Author(s):  
M. Abu-Shady ◽  
E. M. Khokha

In this study, the bound state solutions of the Dirac equation (DE) have been determined with the generalized Cornell potential model (GCPM) under the condition of spin symmetry. The GCPM includes the Cornell potential plus a combination of the harmonic and inversely quadratic potentials. In the framework of the Nikiforov–Uvarov (NU) method, the relativistic and nonrelativistic energy eigenvalues for the GCPM have been obtained. The energies spectra of the Kratzer potential (KP) and the modified Kratzer potential (MKP) have been derived as particular cases of the GCPM. The present results have been applied to some diatomic molecules (DMs) as well as heavy and heavy-light mesons. The energy eigenvalues of the KP and MKP have been computed for several DMs, and they are fully consistent with the results found in the literature. In addition, the energy eigenvalues of the GCPM have been employed for predicting the spin-averaged mass spectra of heavy and heavy-light mesons. One can note that our predictions are in close agreement with the experimental data as well as enhanced compared to the recent studies.


2017 ◽  
Vol 47 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Zakaria M. M. Mahmoud ◽  
Kassem O. Behairy

1992 ◽  
Vol 48 (1) ◽  
pp. 101-105
Author(s):  
B. Ghosh

The method of multiple scales is used to derive a nonlinear Schrödinger equation describing the nonlinear evolution of an ion wave packet propagating along a cylindrical plasma-filled waveguide. Numerical evaluation of nonlinear and dispersive terms shows that the wave is modulationally unstable if the wavenumber exceeds a certain critical value. On comparing with the case of an unbounded plasma, it is shown that finite geometry causes a significant shift of this critical value towards smaller wavenumbers, where Landau damping is relatively small.


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