692 research outputs found
Meson resonances in forward-angle photoproduction
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well with
the experimental data which indicate that the , and waves are
dominated by the , and , resonances
respectively.Comment: 6 pages, 7 figure
Identification of non-ordinary mesons from the dispersive connection between their poles and their Regge trajectories: the f0(500) resonance
We show how the Regge trajectory of a resonance can be obtained from its pole
in a scattering process and analytic constraints in the complex angular
momentum plane. The method is suited for resonances that dominate an elastic
scattering amplitude. In particular, from the rho(770) resonance pole in
pion-pion scattering, we obtain its linear Regge trajectory, characteristic of
ordinary quark-antiquark states. In contrast, the f0(500) pole -the sigma
meson- which dominates scalar isoscalar pion-pion scattering, yields a
non-linear trajectory with a much smaller slope at the f0(500) mass.
Conversely, imposing a linear Regge trajectory for the f0(500), with a slope of
typical size, yields an elastic amplitude at odds with the data. This provides
strong support for the non-ordinary nature of the sigma meson.Comment: 8 pages, 4 figure
Regge trajectory of the f_0(500) resonance from a dispersive connection to its pole
We report here our results on how to obtain the Regge trajectory of a
resonance from its pole in a scattering process by imposing analytic
constraints in the complex angular momentum plane. The method, suited for
resonances that dominate an elastic scattering amplitude, has been applied to
the {\rho}(770) and the f_0(500) resonances. Whereas for the former we obtain a
linear Regge trajectory, characteristic of ordinary quark-antiquark states, for
the latter we find a non-linear trajectory with a much smaller slope at the
resonance mass. This provides a strong indication of the non-ordinary nature of
the sigma meson.Comment: 4 pages, 2 figures, to appear in the proceedings of the "Seventh
International Symposium on Chiral Symmetry in Hadrons and Nuclei
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