2,547 research outputs found
Green's function method for strength function in three-body continuum
Practical methods to compute dipole strengths for a three-body system by
using a discretized continuum are analyzed. New techniques involving Green's
function are developed, either by correcting the tail of the approximate wave
function in a direct calculation of the strength function or by using a
solution of a driven Schroedinger equation in a summed expression of the
strength. They are compared with the complex scaling method and the Lorentz
integral transform, also making use of a discretized continuum. Numerical tests
are performed with a hyperscalar three-body potential in the
hyperspherical-harmonics formalism. They show that the Lorentz integral
transform method is less practical than the other methods because of a
difficult inverse transform. These other methods provide in general comparable
accuracies.Comment: 22 pages, 8 figures, to appear in Progress of Theoretical Physic
Alpha-cluster structure and density wave in oblate nuclei
Pentagon and triangle shapes in Si-28 and C-12 are discussed in relation with
nuclear density wave. In the antisymmetrized molecular dynamics calculations,
the band in Si-28 and the band in C-12 are described by
the pentagon and triangle shapes, respectively. These negative-parity bands can
be interpreted as the parity partners of the ground bands and they
are constructed from the parity-asymmetric-intrinsic states. The pentagon and
the triangle shapes originate in 7alpha and 3alpha cluster structures,
respectively. In a mean-field picture, they are described also by the static
one-dimensional density wave at the edge of the oblate states. In analysis with
ideal alpha cluster models using Brink-Bloch cluster wave functions and that
with a simplified model, we show that the static edge density wave for the
pentagon and triangle shapes can be understood by spontaneous breaking of axial
symmetry, i.e., the instability of the oblate states with respect to the edge
density wave. The density wave is enhanced in the Z=N nuclei due to the
proton-neutron coherent density waves, while it is suppressed in Z\ne N nuclei.Comment: 23 pages, 8 figure
nature of the superdeformed band of and the evolution of the molecular structure
The relation between the superdeformed band of and molecular bands is studied by the deformed-base
antisymmetrized molecular dynamics with the Gogny D1S force. It is found that
the obtained superdeformed band members of have considerable
amount of the component. Above the superdeformed
band, we have obtained two excited rotational bands which have more prominent
character of the molecular band. These three
rotational bands are regarded as a series of
molecular bands which were predicted by using the unique
- optical potentil. As the excitation energy and principal
quantum number of the relative motion increase, the cluster structure becomes more prominent but at the same time, the band
members are fragmented into several states
The {\alpha}-Decay Chains of the Isotopes using Relativistic Mean Field Theory
We study the binding energy, root-mean-square radius and quadrupole
deformation parameter for the synthesized superheavy element Z = 115, within
the formalism of relativistic mean field theory. The calculation is dones for
various isotopes of Z = 115 element, starting from A = 272 to A = 292. A
systematic comparison between the binding energies and experimental data is
made.The calculated binding energies are in good agreement with experimental
result. The results show the prolate deformation for the ground state of these
nuclei. The most stable isotope is found to be 282115 nucleus (N = 167) in the
isotopic chain. We have also studied Q{\alpha} and T{\alpha} for the
{\alpha}-decay chains of 115.Comment: 12 Pages 6 Figures 3 Table
Galactic Center Radio Constraints on Gamma-Ray Lines from Dark Matter Annihilation
Recent evidence for one or more gamma-ray lines at ~ 130 GeV in the Fermi-LAT
data from the Galactic Center has been interpreted as a hint for dark matter
annihilation to Z{\gamma} or H{\gamma} with an annihilation cross section,
~ 10^{-27} cm^3 s^{-1} . We test this hypothesis by comparing
synchrotron fluxes due to the electrons and positrons from the decay of the Z
or the H boson only in the Galactic Center against radio data from the same
region in the Galactic Center. We find that the radio data from single dish
telescopes marginally constrain this interpretation of the claimed gamma lines
for a contracted NFW profile. Already-operational radio telescopes such as LWA,
VLA-Low and LOFAR, and future radio telescopes like SKA, which are sensitive to
annihilation cross sections as small as 10^{-28} cm^3 s^{-1}, can confirm or
rule out this scenario very soon. We discuss the assumptions on the dark matter
profile, magnetic fields, and background radiation density profiles, and show
that the constraints are relatively robust for any reasonable assumptions.
Independent of the above said recent developments, we emphasize that our radio
constraints apply to all models where dark matter annihilates to Z{\gamma} or
H{\gamma}.Comment: v3: 18 pages, 7 figures. Minor changes. Published in Phys. Rev.
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