302 research outputs found
Centroids of Gamow-Teller transitions at finite temperature in fp-shell neutron-rich nuclei
The temperature dependence of the energy centroids and strength distributions
for Gamow-Teller (GT) excitations in several fp-shell nuclei is studied.
The quasiparticle random phase approximations (QRPA) is extended to describe GT
states at finite temperature. A shift to lower energies of the GT strength
is found, as compared to values obtained at zero temperature.Comment: 12 pages, contains 3 tables. E-mail: [email protected],
[email protected]
The Friedrichs-Model with fermion-boson couplings II
In this work we present a formal solution of the extended version of the
Friedrichs Model. The Hamiltonian consists of discrete and continuum bosonic
states, which are coupled to fermions. The simultaneous treatment of the
couplings of the fermions with the discrete and continuous sectors of the
bosonic degrees of freedom leads to a system of coupled equations, whose
solutions are found by applying standard methods of representation of bound and
resonant states.Comment: 13 page
Perturbative description of nuclear double beta decay transitions
A consistent treatment of intrinsic and collective coordinates is applied to
the calculation of matrix elements describing nuclear double beta decay
transitions. The method, which was developed for the case of nuclear rotations,
is adapted to include isospin and number of particles degrees of freedom. It is
shown that the uncertainties found in most models, in dealing with these decay
modes, are largely due to the mixing of physical and spurious effects in the
treatment of isospin dependent interactions.Comment: 4 pages, 2 figures, RevTe
Double beta decay and the proton-neutron residual interaction
The validity of the pn-QRPA and -RQRPA descriptions of double beta decay
transition amplitudes is analyzed by using an exactly solvable model. It is
shown that the collapse of the QRPA is physically meaningful and that it is
associated with the appearance of a state with zero energy in the spectrum. It
is shown that in the RQRPA this particular feature is not present and that this
approach leads to finite but otherwise spurious results for the double beta
decay transition amplitudes near the point of collapse.Comment: LaTeX, 10 pages plus 3 fugures as LaTeX files. Accepted for
publication in Physics Letters
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