1,756 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.
K* resonance effects on direct CP violation in B -> pi pi K
Charged and neutral B decays into two charged pions and a charged or a
neutral kaon are analyzed within the QCD factorization scheme where final state
interactions before and after hadronization are included. The K*(892) and
K*(1430) resonance effects are taken into account using the presently known
pion-Kaon strange vector and scalar form factors. The weak decay amplitudes,
which are calculated at leading power in Lambda_QCD/m_b and at the
next-to-leading order in the strong coupling constant, include the hard
scattering and annihilation contributions. The end point divergences of these
weak final state interactions are controlled by two complex parameters
determined through a fit to the available effective mass and helicity angle
distribution, CP asymmetry and K*(892) branching ratio data. The predicted
K*(1430) branching ratios and the calculated direct CP violation asymmetries
are compared to the Belle and BABAR Collaboration data.Comment: Comments: 22 pages, 2 figures and 3 tables. In this new version, the
results are unchanged, but, the last paragraph of the Section "RESULTS AND
SUMMARY" (now called "RESULTS AND DISCUSSION") has been replaced by a new
Section "SUMMARY AND OUTLOOK". To appear in Physical Review
Resonances and weak interactions in decays
We describe the -wave in decays using
a unitary model for the Final State Interactions (FSI). The three body
decay is treated as a quasi two-body process where, at the weak vertex, the D
meson decays into a resonance and a pion. The weak part of the decay amplitude
is evaluated using the effective weak Hamiltonian within the factorization
approximation.Comment: 4 pages. Contribution to the X Hadron Physics, Florianopolis-Brazil,
March 26-31, 200
Amplitudes Fitted to Experimental Data and to Roy's Equations
The scalar-isoscalar, scalar-isotensor and vector-isovector pi-pi amplitudes
are fitted simultaneously to experimental data and to Roy's equations. The
resulting amplitudes are compared with those fitted only to experimental data.
No additional constraints for the pi-pi threshold behaviour of the amplitudes
are imposed. Threshold parameters are calculated for the amplitudes in the
three waves. Spectrum of scalar mesons below 1.8 GeV is found from the analysis
of the analytical structure of the fitted amplitudes.Comment: 3 pages, 1 figure. Talk given at MESON 2004: 8th International
Workshop on Meson Production, Properties and Interactions, Cracow, Poland,
4-8 Jun 2004. Submitted to Int.J.Mod.Phys.
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