714 research outputs found
Calculation of hyperfine splitting in mesons using configuration interaction approach
The spin - spin mass splitting of light, heavy and mixed mesons are described
within a good accuracy in the potential model with screened potential. We
conclude that the long - distance part of the potential cannot be pure scalar
and that a vector - scalar mixture is favoured. With the same parameters which
gives correct average mass spectrum excellent spin - spin splittings of heavy
quarkonia is obtained. The results are obtained by going beyond usually used
perturbation method, namely using configuration interaction approach.Comment: 8 pages, LaTe
The soft and the hard pomerons: elastic scattering and unitarisation
The hard pomeron component needed to reproduce small-x data seems to be
present in elastic scattering at moderate energy. If this is the case, it is
likely that the total cross section at the LHC will be appreciably larger than
previously expected.Comment: Talk given at 12th International Conference on Elastic and
Diffractive Scattering: Forward Physics and QCD, Hamburg, DESY, Germany,
21-25 May 200
Hard pomeron contribution to forward elastic scattering
The introduction of a hard singularity in fits to total cross sections and to
the ratio of real to imaginary parts enables to reproduce perfectly the data
for sqrt(s)< 100 GeV using only simple-pole parametrisations, both for the soft
and for the hard pomerons.Comment: Contribution to the proceedings of the XIth International Conference
on Elastic and Diffractive Scattering, Chateau de Blois, France, May 15 - 20,
2005. Needs Blois.sty (provided
Turing Instability in a Boundary-fed System
The formation of localized structures in the chlorine dioxide-idodine-malonic
acid (CDIMA) reaction-diffusion system is investigated numerically using a
realistic model of this system. We analyze the one-dimensional patterns formed
along the gradients imposed by boundary feeds, and study their linear stability
to symmetry-breaking perturbations (Turing instability) in the plane transverse
to these gradients. We establish that an often-invoked simple local linear
analysis which neglects longitudinal diffusion is inappropriate for predicting
the linear stability of these patterns. Using a fully nonuniform analysis, we
investigate the structure of the patterns formed along the gradients and their
stability to transverse Turing pattern formation as a function of the values of
two control parameters: the malonic acid feed concentration and the size of the
reactor in the dimension along the gradients. The results from this
investigation are compared with existing experiments.Comment: 41 pages, 18 figures, to be published in Physical Review
From Regge Behavior to DGLAP Evolution
We study the interface between Regge behavior and DGLAP evolution in a
non-perturbative model for the nucleon structure function based on a multipole
pomeron exchange. This model provides the input for a subsequent DGLAP
evolution that we calculate numerically. The soft input and its evolution give
a good fit to the experimental data in the whole available range of x and Q^2.Comment: 7 pages, LaTeX, 4 figures. Text improved and reduced, figures
modified, references updated. To be published in Eur. Phys. J. C in the
present for
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