378 research outputs found
High-K Precession modes: Axially symmetric limit of wobbling motion
The rotational band built on the high-K multi-quasiparticle state can be
interpreted as a multi-phonon band of the precession mode, which represents the
precessional rotation about the axis perpendicular to the direction of the
intrinsic angular momentum. By using the axially symmetric limit of the
random-phase-approximation (RPA) formalism developed for the nuclear wobbling
motion, we study the properties of the precession modes in W; the
excitation energies, B(E2) and B(M1) values. We show that the excitations of
such a specific type of rotation can be well described by the RPA formalism,
which gives a new insight to understand the wobbling motion in the triaxial
superdeformed nuclei from a microscopic view point.Comment: 14 pages, 8 figures (Spelling of the authors name was wrong at the
first upload, so it is corrected
The generalised relativistic Lindhard functions
We present here analytic expressions for the generalised Lindhard function,
also referred to as Fermi Gas polarisation propagator, in a relativistic
kinematic framework and in the presence of various resonances and vertices.
Particular attention is payed to its real part, since it gives rise to
substantial difficulties in the definition of the currents entering the
dynamics.Comment: 48 pages, 2 figures, to be published in EPJ
The mean energy, strength and width of triple giant dipole resonances
We investigate the mean energy, strength and width of the triple giant dipole
resonance using sum rules.Comment: 12 page
Effects of the Neutron Spin-Orbit Density on Nuclear Charge Density in Relativistic Models
The neutron spin-orbit density contributes to the nuclear charge density as a
relativistic effect. The contribution is enhanced by the effective mass
stemming from the Lorentz-scalar potential in relativistic models. This
enhancement explains well the difference between the cross sections of elastic
electron scattering off Ca and Ca which was not reproduced in
non-relativistic models. The spin-orbit density will be examined in more detail
in electron scattering off unstable nuclei which would be available in the
future.Comment: 4 pages with 3 eps figures, revte
Development of a low-background HPGe detector at Kamioka Observatory
A new ultra-low background high-purity germanium (HPGe) detector has been
installed at the Kamioka underground experimental site. The background count
rate in the energy range from 40 keV to 2700 keV is about 25% lower than that
of the first HPGe detector installed in 2016, which has the same detector
specification and similar shielding geometry. This paper describes the
shielding configuration, including the cleaning of the material surface, the
comparison of calibration data and simulation, the time variation of the
background spectra, the sample measurement procedure, and some results of the
radioactivity in the selected samples
Microscopic description of the surface dipole plasmon in large Na_N clusters (950 < N < 12050)
Fully microscopic RPA/LDA calculations of the dipole plasmon for very large
neutral and charged sodium clusters, Na_N^Z+, in the size range 950
< N < 12050 are presented for the first time. 60 different sizes are
considered altogether, which allows for an in-depth investigation of the
asymptotic behavior of both the width and the position of the plasmon.Comment: Latex/Revtex, 4 pages with 4 Postscript figures, accepted for
publication in Physical Review
QCD Sum Rules, Scattering Length and the Vector Mesons in Nuclear Medium
Critical examination is made on the relation between the mass shift of vector
mesons in nuclear medium and the vector-meson nucleon scattering length. We
give detailed comparison between the QCD sum rule approach by two of the
present authors (Phys. Rev. {\bf C46} (1992) R34) and the scattering-length
approach by Koike (Phys. Rev. {\bf C51} (1995) 1488). It is shown that the
latter approach is mortally flawed both technically and conceptually.Comment: 16 pages, latex, 4 figures appended as uu-encoded fil
Modified Quark-Meson Coupling Model for Nuclear Matter
The quark-meson coupling model for nuclear matter, which describes nuclear
matter as non-overlapping MIT bags bound by the self-consistent exchange of
scalar and vector mesons, is modified by introducing medium modification of the
bag constant. We model the density dependence of the bag constant in two
different ways: one invokes a direct coupling of the bag constant to the scalar
meson field, and the other relates the bag constant to the in-medium nucleon
mass. Both models feature a decreasing bag constant with increasing density. We
find that when the bag constant is significantly reduced in nuclear medium with
respect to its free-space value, large canceling isoscalar Lorentz scalar and
vector potentials for the nucleon in nuclear matter emerge naturally. Such
potentials are comparable to those suggested by relativistic nuclear
phenomenology and finite-density QCD sum rules. This suggests that the
reduction of bag constant in nuclear medium may play an important role in low-
and medium-energy nuclear physics.Comment: Part of the text is reordered, revised version to appear in Phys.
Rev. C. 19 pages, ReVTeX, 4 figures embedde
Tensor Coupling and Vector Mesons in Dense Nuclear Matter
The effects of magnetic interaction between vector mesons and nucleons on the
propagation (mass and width) of the -meson in particular moving through
very dense nuclear matter is studied and the modifications, qualitative and
quantitative, due to the relevant collective modes (zero-sound and plasma
frequencies) of the medium discussed. It is shown that the -mesons
produced in high-energy nuclear collisions will be longitudinally polarized in
the region of sufficiently dense nuclear matter, in the presence of such an
interaction.Comment: Plain Latex file. Three figures, not appended, may be obtained on
request to [email protected]
Electromagnetic form factors of the bound nucleon
We calculate electromagnetic form factors of the proton bound in specified
orbits for several closed shell nuclei. The quark structure of the nucleon and
the shell structure of the finite nuclei are given by the QMC model. We find
that orbital electromagnetic form factors of the bound nucleon deviate
significantly from those of the free nucleon.Comment: 12 pages including 4 ps figure
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