7,084 research outputs found
Theory of Complex Scattering Lengths
We derive a generalized Low equation for the T-matrix appropriate for complex
atom-molecule interaction. The properties of this new equation at very low
energies are studied and the complex scattering length and effective range are
derived.Comment: 9 page
Toward a microscopic description of reactions involving exotic nuclei
We propose an extension of the Continuum Discretized Coupled Channels (CDCC)
method, where the projectile is described by a microscopic cluster model. This
microscopic generalization (MCDCC) only relies on nucleon-target interactions,
and therefore presents an important predictive power. Core excitations can be
included without any further parameter. As an example we investigate the
\lipb elastic scattering at and 35 MeV. The Li nucleus is
known to present an cluster structure, and is well described by the
Resonating Group Method. An excellent agreement is obtained for the \lipb
elastic cross sections, provided that breakup channels are properly included.
We also present an application to inelastic scattering, and discuss future
applications of the MCDCC.Comment: 5 pages, 3 figures, Physical Review Letters (2013) in pres
Ultra cold neutrons: determination of the electric dipole moment and gravitational corrections via matter wave interferometry
We propose experiments using ultra cold neutrons which can be used to
determine the electric dipole moment of the neutron itself, a well as to test
corrections to gravity as they are foreseen by string theories and Kaluza-Klein
mechanisms.Comment: 3 pages, no figures, reference adde
Condensed vortex ground states of rotating Bose-Einstein condensate in harmonic atomic trap
We study a system of Bose atoms trapped by a symmetric harmonic
potential, interacting via weak central forces. Considering the ground state of
the rotating system as a function of the two conserved quantities, the total
angular momentum and its collective component, we develop an algebraic approach
to derive exact wave functions and energies of these ground states. We describe
a broad class of the interactions for which these results are valid. This
universality class is defined by simple integral condition on the potential.
Most of the potentials of practical interest which have pronounced repulsive
component belong to this universality class.Comment: 34 pages, 10 ps figures, minor revisions, to be publ. in Ann. Phy
Chaotic behavior of the Compound Nucleus, open Quantum Dots and other nanostructures
It is well established that physical systems exhibit both ordered and chaotic
behavior. The chaotic behavior of nanostructure such as open quantum dots has
been confirmed experimentally and discussed exhaustively theoretically. This is
manifested through random fluctuations in the electronic conductance. What
useful information can be extracted from this noise in the conductance? In this
contribution we shall address this question. In particular, we will show that
the average maxima density in the conductance is directly related to the
correlation function whose characteristic width is a measure of energy- or
applied magnetic field- correlation length. The idea behind the above has been
originally discovered in the context of the atomic nucleus, a mesoscopic
system. Our findings are directly applicable to graphene.Comment: 10 pages, 5 figures. Contribution to: "4th International Workshop on
Compound-Nuclear Reactions and Related Topics (CNR*13)", October 7-11, 2013,
Maresias, Brazil. To appear in the proceeding
Optimal network topologies for information transmission in active networks
This work clarifies the relation between network circuit (topology) and
behavior (information transmission and synchronization) in active networks,
e.g. neural networks. As an application, we show how to determine a network
topology that is optimal for information transmission. By optimal, we mean that
the network is able to transmit a large amount of information, it possesses a
large number of communication channels, and it is robust under large variations
of the network coupling configuration. This theoretical approach is general and
does not depend on the particular dynamic of the elements forming the network,
since the network topology can be determined by finding a Laplacian matrix (the
matrix that describes the connections and the coupling strengths among the
elements) whose eigenvalues satisfy some special conditions. To illustrate our
ideas and theoretical approaches, we use neural networks of electrically
connected chaotic Hindmarsh-Rose neurons.Comment: 20 pages, 12 figure
How large is the spreading width of a superdeformed band?
Recent models of the decay out of superdeformed bands can broadly be divided
into two categories. One approach is based on the similarity between the
tunneling process involved in the decay and that involved in the fusion of
heavy ions, and builds on the formalism of nuclear reaction theory. The other
arises from an analogy between the superdeformed decay and transport between
coupled quantum dots. These models suggest conflicting values for the spreading
width of the decaying superdeformed states. In this paper, the decay of
superdeformed bands in the five even-even nuclei in which the SD excitation
energies have been determined experimentally is considered in the framework of
both approaches, and the significance of the difference in the resulting
spreading widths is considered. The results of the two models are also compared
to tunneling widths estimated from previous barrier height predictions and a
parabolic approximation to the barrier shape
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