57,151 research outputs found
Screened potential and the baryon spectrum
We show that in a quark model scheme the use of a screened potential,
suggested by lattice QCD, instead of an infinitely rising one with the
interquark distance, provides a more adequate description of the high-energy
baryon spectrum. In particular an almost perfect parallelism between the
predicted and observed number of states comes out throwing new light about the
so-called missing resonance problem.Comment: 11 pages, 6 figures, accepted for publication in Phys. Rev.
Renormalization group analysis of electrons near a Van Hove singularity.
A model of interacting two dimensional electrons near a Van Hove singularity
is studied, using renormalization group techniques. In hole doped systems, the
chemical potential is found to be pinned near the singularity, when the
electron-electron interactions are repulsive. The RG treatment of the leading
divergences appearing in perturbation theory give rise to marginal behavior and
anisotropic superconductivity.Comment: 4 Latex pages + 5 postcript figure
Electrostatic screening in fullerene molecules
The screening properties of fullerene molecules are described by means of a
continuum model which uses the electronic wavefunctions of planar graphite as a
starting point. The long distance behavior of the system gives rise to a
renormalizable theory, which flows towards a non trivial fixed point. Its
existence implies an anomalous dielectric constant. The screening properties
are neither metallic nor insulating. Alternatively, the intramolecular
screening is obtained from a simple approximation to the electronic
wavefunctions. Intermolecular effects are also calculated. As a consistency
check, it is shown that the observed polarizability of C is well
eproduced.Comment: 7 pages. Revte
Few-anyon systems in a parabolic dot
The energy levels of two and three anyons in a two-dimensional parabolic
quantum dot and a perpendicular magnetic field are computed as power series in
1/|J|, where J is the angular momentum. The particles interact repulsively
through a coulombic (1/r) potential. In the two-anyon problem, the reached
accuracy is better than one part in 10^5. For three anyons, we study the
combined effects of anyon statistics and coulomb repulsion in the ``linear''
anyonic states.Comment: LaTeX, 6 pages, 4 postscript figure
Renormalizing Sznajd model on complex networks taking into account the effects of growth mechanisms
We present a renormalization approach to solve the Sznajd opinion formation
model on complex networks. For the case of two opinions, we present an
expression of the probability of reaching consensus for a given opinion as a
function of the initial fraction of agents with that opinion. The calculations
reproduce the sharp transition of the model on a fixed network, as well as the
recently observed smooth function for the model when simulated on a growing
complex networks.Comment: 5 pages, 7 figure
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