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New Solutions for Scalar-Isoscalar pi-pi Phase Shifts

R. Kaminski·L. Lesniak·K. Rybicki
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Abstract

The scalar-isoscalar pi-pi phase shifts are calculated in the pi-pi energy range from 600 MeV to 1600 MeV. We use results of the CERN-Cracow-Munich collaboration for the reaction pi^- p --> pi^+ pi^- n on a transversely polarized target at 17.2 GeV/c pi^- momentum. Energy-independent separation of the S-wave pseudoscalar amplitude (pi exchange) from the pseudovector amplitude (a_1 exchange) is carried out. Below the KK threshold we find two solutions for the pi-pi phase shifts, for which the phases increase slower with the effective pi-pi mass than the P-wave phases ("flat" solutions) and two solutions for which the phases increase faster than the P-wave phases ("steep" solutions). Above 1420 MeV both sets of phase shifts increase with energy faster than in the experiment on an unpolarized target. This fact can be related to a presence of the scalar resonance f_0(1500).

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R. Kaminski, L. Lesniak, K. Rybicki. 1997-12-11. New Solutions for Scalar-Isoscalar pi-pi Phase Shifts. https://doi.org/10.1063/1.56061

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