60,301 research outputs found
Randomly interacting bosons, mean-fields and L=0 ground states
Random interactions are used to investigate to what extent the low-lying
behavior of even-even nuclei depend on particular nucleon-nucleon interactions.
The surprising results that were obtained for the interacting boson model, i.e.
the dominance of ground states with L=0 and the occurrence of both vibrational
and rotational structure, are interpreted and explained in terms of a
mean-field analysis.Comment: 6 pages, 2 figures, Invited talk at NP2001, Goettingen, March 2001,
World Scientific (2001), in pres
How random are random nuclei? Shapes, triangles and kites
We study the origin of the regular features obtained in numerical studies of
the IBM with random interactions, in particular the dominance of L=0 ground
states and the occurrence of vibrational and rotational band structures. It is
shown that the geometric shapes associated with IBM Hamiltonians play a crucial
role in understanding these regular properties. Different regions of the
parameter space are associated with definite geometric shapes, such as
spherical and deformed shapes and a condensate of quadrupole bosons.Comment: 5 pages, 3 figures, invited talk at `International Conference on
Nuclear Structure, May 22-25, Wyoming, US
Collective states from random interactions
The anharmonic vibrator and rotor regions in nuclei are investigated in the
framework of the interacting boson model using an ensemble of random one- and
two-body interactions. Despite the randomness of the interactions (in sign and
size) we find a predominance of L(P)=0(+) ground states and strong evidence for
the occurrence of both vibrational and rotational band structure.Comment: 4 pages, 2 figures, 1 tables, to be published in the proceedings of
Bologna 200
Scalar Wave Propagation in Random, Amplifying Media: Influence of Localization Effects on Length and Time Scales and Threshold Behavior
We present a detailed discussion of scalar wave propagation and light
intensity transport in three dimensional random dielectric media with optical
gain. The intrinsic length and time scales of such amplifying systems are
studied and comprehensively discussed as well as the threshold characteristics
of single- and two-particle propagators. Our semi-analytical theory is based on
a self-consistent Cooperon resummation, representing the repeated
self-interference, and incorporates as well optical gain and absorption,
modeled in a semi-analytical way by a finite imaginary part of the dielectric
function. Energy conservation in terms of a generalized Ward identity is taken
into account
New correlations induced by nuclear supersymmetry
We show that the nuclear supersymmetry model (n-susy) in its extended
version, predicts correlations in the nuclear structure matrix elements which
characterize transfer reactions between nuclei that belong to the same
supermultiplet. These correlations are related to the fermionic generators of
the superalgebra and if verified experimentally can provide a direct test of
the model.Comment: Invited talk at "Nuclear Physics: Large and Small", April 19-22,
2004, Hacienda Cocoyoc, Mexic
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