ar X iv : h ep - p h / 97 12 33 7 v 1 1 1 D ec 1 99 7 Analysis of New Results For Scalar - Isoscalar ππ Phase Shifts
نویسنده
چکیده
The scalar – isoscalar ππ phase shifts are analysed using a separable potential model of three coupled channels (ππ , KK and an effective 2π2π system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the πp↑ → π πn reaction on a polarized target. A relatively narrow (90 – 180 MeV) scalar resonance f0(1400− 1460) is found, together with a wide f0(500) (Γ ≈ 500 MeV) and the narrow f0(980) state. Recently the CERN-Cracow-Munich data [1] for the πp↑ → π πn reaction on a polarized target were analysed in Ref. [2]. Four solutions for the isoscalar S-wave phase shifts from the ππ threshold up to 1600 MeV were found and two of them, called ”down-flat” and ”up-flat” fully satisfy unitarity constraints. The ”down-flat” solution is in good agreement with the former solution of Ref. [3] below 1400 MeV. In Ref. [4] the scalar meson spectrum was studied in terms of a relativistic ππ and KK coupled channel model from the ππ threshold up to 1400 MeV. Strong four–pion production, observed in different experiments [5–9], provides a compelling argument to take into account the 4π channel. In this report we extend the isoscalar S–wave 2–channel model of Ref. [4] by adding to its ππ and KK̄ channels an effective third coupled channel, here called σσ. We consider the S-wave scattering and transition reactions between three coupled channels of meson pairs labelled 1, 2 and 3. Reaction amplitudes T satisfy a system of coupled channel Lippmann-Schwinger equations [4] with a separable form of the interaction:
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ar X iv : h ep - p h / 97 12 33 7 v 2 1 1 D ec 1 99 7 Analysis of New Results For Scalar - Isoscalar ππ Phase Shifts
The scalar – isoscalar ππ phase shifts are analysed using a separable potential model of three coupled channels (ππ , KK and an effective 2π2π system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the πp↑ → π πn reaction on a polarized target. A relatively narrow (90 – 180 MeV) scalar resonance f0(1400− 1460) is fou...
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