3,819 research outputs found
Gamow-Teller strength distributions for double-beta-decaying nuclei within continuum-QRPA
A version of the pn-continuum-QRPA is outlined and applied to describe the
Gamow-Teller strength distributions for -decaying open-shell
nuclei. The calculation results obtained for the pairs of nuclei Cd-Sn
and Te-Xe are compared with available experimental data.Comment: 8 pages, 3 figures, To appear in the proceedings of "Nucleus-2007:
Fundamental problems of nuclear physics, atomic power engineering and nuclear
technologies" Voronezh, Russia, June 25-29, 200
Phosphorene nanoribbons
Edge-induced gap states in finite phosphorene layers are examined using
analytical models and density functional theory. The nature of such gap states
depends on the direction of the cut. Armchair nanoribbons are insulating,
whereas nanoribbons cut in the perpendicular direction (with zigzag and
cliff-type edges) are metallic, unless they undergo a reconstruction or
distortion with cell doubling, which opens a gap. All stable nanoribbons with
unsaturated edges have gap states that can be removed by hydrogen passivation.
Armchair nanoribbon edge states decay exponentially with the distance to the
edge and can be described by a nearly-free electron model
Sensitive behavior of -decay amplitude within QRPA and broken SU(4) symmetry in nuclei
Making use of an identity transformation independent of a nuclear model, we
represent the {\bb}-amplitude as a sum of two terms. One term accounts for most
of the sensitivity of the original {\bb}-amplitude to for realistic
(with being the ratio of the triplet and singlet
p-p interaction strengths) and is determined by a specific energy-weighted sum
rule. The sum rule depends only on the particle-particle residual interaction
(being linear function of in the QRPA) and passes through zero at the
point where the Wigner SU(4) symmetry is restored in the p-p sector
of the Hamiltonian. The second term in the decomposition of the {\bb}-amplitude
is demonstrated within the QRPA to be a much smoother function for the
realistic values of than the original {\bb}-amplitude. This term is
mainly determined by the intensity of the spin-orbit interaction of the nuclear
mean field. Thus, the analysis of the present work reveals the reasons for the
sensitivity of the {\bb}-amplitude to different components of the nuclear
Hamiltonian and thereby can help in constraining nuclear model uncertainties in
calculations of the amplitude.Comment: 14 pages, 3 figures; to be published in Nucl. Phys.
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