1,221 research outputs found
The Yrast Spectra of Weakly Interacting Bose-Einstein Condensates
The low energy quantal spectrum is considered as a function of the total
angular momentum for a system of weakly interacting bosonic atoms held together
by an external isotropic harmonic potential. It is found that besides the usual
condensation into the lowest state of the oscillator, the system exhibits two
additional kinds of condensate and associated thermodynamic phase transitions.
These new phenomena are derived from the degrees of freedom of "partition
space" which describes the multitude of different ways in which the angular
momentum can be distributed among the atoms while remaining all the time in the
lowest state of the oscillator
Low-energy M1 and E3 excitations in the proton-rich Kr-Zr region
Low-energy intrinsic =1, , , , and states in
the even-even proton-rich Sr, Kr, and Zr nuclei are investigated using the
quasiparticle random phase approximation. In the ZN nuclei the
lowest-lying 1 states are found to carry unusually large strength.
It is demonstrated that, unlike in the heavier nuclei, the octupole
collectivity in the light zirconium region is small and, thus, is not directly
correlated with the systematics of the lowest negative parity states.Comment: 15pages, REVTEX 3.0, JIHIR(ORNL) Document no.93-17, Postscript files
for 14 figures are available on request from T.Nakatsusaka at
[email protected]
Rotations of nuclei with reflection asymmetry correlations
We propose a collective Hamiltonian which incorporates interactions capable
to generate rotations in nuclei with simultaneous presence of octupole and
quadrupole deformations. It is demonstrated that the model formalism could be
applied to reproduce the staggering effects observed in nuclear octupole bands.
On this basis we propose that the interactions involved would provide a
relevant handle in the study of collective phenomena in nuclei and other
quantum mechanical systems with reflection asymmetry correlations.Comment: LaTeX, 9 pages plus 3 figures given in separate .ps files. To appear
in the proceedings of the International Conference on Nuclear Structure and
Related Topics (Dubna, Russia, 6-10/6/2000), ed. R. Jolos, V. Voronov, et a
Cranked Hartree-Fock-Bogoliubov Calculation for Rotating Bose-Einstein Condensates
A rotating bosonic many-body system in a harmonic trap is studied with the
3D-Cranked Hartree-Fock-Bogoliubov method at zero temperature, which has been
applied to nuclear many-body systems at high spin. This method is a variational
method extended from the Hartree-Fock theory, which can treat the pairing
correlations in a self-consistent manner. An advantage of this method is that a
finite-range interaction between constituent particles can be used in the
calculation, unlike the original Gross-Pitaevskii approach. To demonstrate the
validity of our method, we present a calculation for a toy model, that is, a
rotating system of ten bosonic particles interacting through the repulsive
quadrupole-quadrupole interaction in a harmonic trap. It is found that the
yrast states, the lowest-energy states for the given total angular momentum,
does not correspond to the Bose-Einstein condensate, except a few special
cases. One of such cases is a vortex state, which appears when the total
angular momentum is twice the particle number (i.e., ).Comment: accepted to Phys. Rev.
Anomalous Crossing Frequency in Odd Proton Nuclei
A generic explanation for the recently observed anomalous crossing
frequencies in odd proton rare earth nuclei is given. As an example, the proton
band in Ta is discussed in detail by using the
angular momentum projection theory. It is shown that the quadrupole pairing
interaction is decisive in delaying the crossing point and the changes in
crossing frequency along the isotope chain are due to the different neutron
shell fillings
Pairing and continuum effects on low-frequency quadrupole vibrations in deformed Mg isotopes close to the neutron drip line
Low-frequency quadrupole vibrational modes in deformed Mg close
to the neutron drip line are studied by means of the quasiparticle-random-phase
approximation based on the coordinate-space Hartree-Fock-Bogoliubov formalism.
Strongly collective and excitation modes carrying 10-20
Weisskopf units in the intrinsic isoscalar quadrupole transition strengths are
obtained at about 3 MeV. There are two reasons for the enhancement of the
transition strengths. First, the quasiparticle wave functions generating these
modes possess spatially very extended structure. The asymptotic selection rules
characterizing the and vibrations in stable deformed nuclei
are thus strongly violated. Second, the dynamic pairing effects act strongly to
enhance the collectivity of these modes. It is suggested that the lowest
collective mode is a particularly sensitive indicator of the
nature of pairing correlations in deformed nuclei close to the neutron drip
line.Comment: 23 pages including 11 figures and 8 tables. Submitted to NP
Superconformal Symmetry, The Supercurrent And Non-BPS Brane Dynamics
The Noether currents associated with the non-linearly realized
super-Poincare' symmetries of the Green-Schwarz (Nambu-Goto-Akulov-Volkov)
action for a non-BPS p=2 brane embedded in a N=1, D=4 target superspace are
constructed. The R symmetry current, the supersymmetry currents, the
energy-momentum tensor and the scalar central charge current are shown to be
components of a world volume supercurrent. The centrally extended
superconformal transformations are realized on the Nambu-Goldstone boson and
fermion fields of the non-BPS brane. The superconformal currents form
supersymmetry multiplets with the world volume conformal central charge current
and special conformal current being the primary components of the supersymmetry
multiplets containing all the currents. Correspondingly the superconformal
symmetry breaking terms form supersymmetry multiplets the components of which
are obtainable as supersymmetry transformations of the primary currents'
symmetry breaking terms.Comment: 27 pages, LaTeX, Summary Tables Adde
Can adenine nucleotides predict primary nonfunction of the human liver homograft?
Sixty-eight primary liver grafts were analyzed to see whether adenine nucleotides (AN: ATP, ADP, and AMP) or purine catabolites (PC: adenosine, inosine, hypoxanthine, and xanthine) of tissue or effluent can predict primary graft nonfunction. AN, PC, and nicotinamide adenine dinucleotide, oxidized form (NAD+) of the tissue before (pretransplant) and after graft reperfusion (post-transplant) and of the effluent were analyzed. The graft outcome was classified into two groups (group A: successful, n = 64; group B: primary nonfunctioning, n = 4). No significant differences were observed in pretransplant measurements between groups A and B, whereas ATP, ADP, total AN, total AN + total PC (T) and NAD+, in post-transplant tissues, were significantly higher in group A. Xanthine in the effluent was significantly higher in group B than in group A. ATP, ADP, total AN, T, and NAD+ in post-transplant tissue were significantly associated with primary graft nonfunction by logistic regression analysis
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