Analysis of Y-0* (1520) and Determination of the Sigma Parity
Sep 1, 1963
33 pages
Published in:
- Phys.Rev. 131 (1963) 2248-2281
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Abstract: (APS)
The interaction of K− mesons on protons resulting in elastic and charge-exchange scattering and hyperon production are reported for a range of momenta from 250 to 513 MeV/c. About 10 000 events obtained in the Lawrence Radiation Laboratory's 15-in. bubble chamber were analyzed. Differential and total cross sections for all channels are examined. For Σ+π−, Σ0π0, and Λπ0 production, polarization measurements are also available. A resonant state is identified with a mass 1519 MeV and a full width Γ=16 MeV, decaying into K¯N, Σπ, and Λππ in the branching ratio 30:55:15, respectively. The resonance is found to have isotopic spin 0 and spin 32, and its parity is that of the K¯N D32 state. By use of the polarization arising from the D32−S-wave interference, a strong argument for negative KNΣ parity is obtained. All the data are fitted to a model based on a Breit-Wigner resonant amplitude and nonresonant S, P, and D amplitudes, parametrized by constant scattering lengths. An extensive search for χ2 minima was done on an IBM-7090 computer under various assumptions for the spin and parity of the resonance. Only the D32 possibility in both K−p and Σπ states yields a satisfactory (43% probability) fit. A D52 K−p resonance (with Σπ in F52) is the nearest alternative possibility, with a likelihood of less than 1% of fitting the data.References(23)
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