1,556 research outputs found
Peculiarities in multichannel interaction amplitudes for meson-meson scattering and scalar meson spectroscopy
Interactions in coupled channels pipi, KKbar and an effective 2pi2pi in
scalar-isoscalar wave have been analysed. Influence of interchannel couplings
on analytical structure of multichannel interaction amplitudes has been
studied. Interplay of S-matrix zeroes and poles and their relation with
parameters of scalar resonances has been investigated.Comment: presented by R. Kaminski at the Meson 2000 Conference, Cracow,
Poland, May 19-23, 2000; 5 pages including 2 figures, to appear in Acta
Physica Polonica
Roy's equations and the pion-pion experimental data
Roy's equations are used to check if the scalar-isoscalar pion-pion
scattering amplitudes fitted to experimental data fulfill crossing symmetry
conditions. It is shown that the amplitudes describing the ``down-flat'' phase
shift solution satisfy crossing symmetry below 1 GeV while the amplitudes
fitted to the "up-flat'' data do not. In this way the long standing "up-down"
ambiguity in the phenomenological determination of the scalar-isoscalar
pion-pion amplitudes has been resolved confirming the independent result of the
recent joint analysis of the pi+pi- and pi0pi0 data.Comment: 6 pages, 2 figures, talk given at Tenth International Conference on
Hadron Spectroscopy (Hadron'03), Aschaffenburg, Germany, August 31 -
September 6 200
Multichannel Interaction Analysis of Scalar Mesons Below 1800 MeV
Properties of scalar--isoscalar mesons in a mass range from pi-pi threshold
up to 1800 MeV are analysed using an unitary model with separable interactions
in three decay channels: pi-pi, K-anti K and an effective 2pi-2pi. Different
solutions are obtained by fitting pi-pi and K-anti K data. Analytical structure
of the meson-meson multichannel amplitudes is studied with a special emphasis
on the important role played by the S-matrix zeroes. The dependence of the
positions of S-matrix singularities on the interchannel coupling strength is
investigated. Poles, located in the complex energy plane not too far from the
physical region, are interpreted as scalar resonances: a wide f0(500), a narrow
f0(980) and a relatively narrow f0(1400). In all our solutions two resonances,
lying on different sheets, in the energy region between 1300 MeV and 1500 MeV
are found. These states may be compared with the resonances f0(1370) and
f0(1500) seen in the experiments at CERN. Total, elastic and inelastic channel
cross sections, branching ratios and coupling constants are evaluated and
compared with available data.Comment: Talk given at Workshop on Hadron Spectroscopy, Frascati (Rome) -
Italy, March 8-12, 1999. To be published in Frascati Physics Series, 8 pages,
4 figures, included file frascatiphys.st
Analysis of New Results For Scalar-Isoscalar pi-pi Phase Shifts
The scalar -- isoscalar pi-pi phase shifts are analysed using a separable
potential model of three coupled channels (pipi, KK and an effective 2pi2pi
system). Model parameters are fitted to two sets of solutions obtained in a
recent analysis of the CERN-Cracow-Munich measurements of the pi^- p --> pi^+
pi^- n reaction on a polarized target. A relatively narrow (90 -- 180 MeV)
scalar resonance f_0(1400-1460) is found, together with a wide f_0(500) (Gamma
= 500 MeV) and the narrow f_0(980) state.Comment: 4 pages, 3 figures. Talk given at 7th International Conference on
Hadron Spectroscopy (Hadron 97), Upton, NY, 25-30 Aug 199
pi-pi scattering amplitudes constrained by Roy's equations
The scalar-isoscalar, scalar-isotensor and vector-isovector pi-pi amplitudes
have been fitted simultaneously to experimental data and to to Roy's equations.
Resulting pi-pi phase shifts up to 1600 MeV and near threshold observables have
been analyzed. Only the amplitudes fitted to the "down-flat" set of phase
shifts in scalar-isoscalar wave fulfill crossing symmetry conditions and can be
regarded as physical.Comment: 4 pages, talk presented at 12th International QCD Conference (QCD05)
4-9th July 2005 Montpellier (France), to appear in Nucl. Phys. B (Proc.
Suppl.
Towards a unitary Dalitz plot analysis of three-body hadronic B decays
A unitary model of the final state kaon pion interaction amplitudes in the B
--> K pi pi decays is constructed. The weak decay penguin amplitudes, derived
in QCD factorization, are supplemented by phenomenological contributions. The
strange kaon- pion scalar and vector form factors are used to calculate the
kaon pion effective mass and helicity angle distributions, branching ratios, CP
asymmetries and the phase difference between the B0 and anti B0 decay
amplitudes to K*(892) pi. The fit on the phenomenological parameters leads to a
good agreement with the experimental data, particularly for the
B --> K*(892) pi decays. However, our predicted B+- --> K*0(1430) pi+-,
K*0(1430)--> K+-pi-+ branching fraction is smaller than the results of the
Belle and BaBar collaborations, obtained from isobar model analyses. A new
parameterization of the S-wave kaon- pion effective mass distribution, which
can be used in future experimental Dalitz plot analyses, is proposed.Comment: 5 pages, 1 figure, contribution to Proc. Int. Europhysics Conference
on High Energy Physics (HEP2009), July 16-22, 2009, Krakow, Poland,
PoS(HEP2009)20
Final state interactions and CP violation in B decays to three pseudoscalars
We study CP violation and final state interactions between pions and kaons in
B+, B-, B0 and bar B0 decays into K pi pi. The weak transition amplitudes
consist of two terms: the first part is derived in QCD factorization approach
and the second one is a phenomenological long-distance charming penguin
contribution. The final state K pi interactions in S- and P-waves are described
by strange scalar and vector form factors, respectively. These are determined
using a unitary coupled channel model together with chiral symmetry and
asymptotic QCD constraints. The final state interactions are dominated by
presence of the scalar K*0(1430) and the vector K*(892) resonances. We show
that additional charming penguin amplitudes are needed to reproduce the latest
experimental K pi effective mass and helicity angle distributions, branching
fractions and asymmetries obtained by Belle and BaBar collaborations.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Nov. 29 - Dec. 4 2009, Florida State Universit
Contextual Cognitive Map
The model of cognitive maps introduced by Tolman [1] provides a representation of an influence network between notions. A cognitive map can contain a lot of influences that makes difficult its exploitation. Moreover these influences are not always relevant for different uses of a map. This paper extends the cognitive map model by describing the validity context of each influence with a conceptual graph. A filtering mechanism of the influences according to a use context is provided so as to obtain a simpler and more adjusted map for a user. A prototype that implements this model of contextual cognitive map has been developed
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