An analysis of about 60 000 events produced in the reaction π-A → (π+π-π-)A on nine different nuclear targets A at 8.9, 12.9, and 15.1 GeV/c has been performed using the Illinois PWA program. In the A1 region our "coherent" sample of events (which contains about 11% of incoherently produced events) is described by only four partial waves: the 1+S and 1+P amplitudes, which both show a peak, and the O-S and O-P waves, which are rather constant. We observed variations of both 1+S and 1+P phases relative to the O-P phase by about 90° across the A1 peak. This observation suggests the presence of resonant 1+ waves in the A1 mass region (∼1.1 GeV). In the A3 region we observe that the 2- state shows resonance behaviour and that fπ and ρ{variant}π are two decays modes with amplitudes of opposite signs.
Evidence for resonance behaviour of A1 and A3 mesons coherently produced on nuclei / J. Pernegr, B. Aebischer, K. Freudenreich, R. Frosch, F. Gentit, P. Mühlemann, W. Wetzel, W. Beusch, V. Chaloupka, D. Websdale, P. Astbury, G. Lee, M. Letheren, G. Bellini, M. Di Corato, F. Palombo, P. Rancoita, G. Vegni. - In: NUCLEAR PHYSICS. B. - ISSN 0550-3213. - 134:3(1978), pp. 436-462. [10.1016/0550-3213(78)90458-3]
Evidence for resonance behaviour of A1 and A3 mesons coherently produced on nuclei
G. Bellini;M. Di Corato;F. Palombo;G. Vegni
1978
Abstract
An analysis of about 60 000 events produced in the reaction π-A → (π+π-π-)A on nine different nuclear targets A at 8.9, 12.9, and 15.1 GeV/c has been performed using the Illinois PWA program. In the A1 region our "coherent" sample of events (which contains about 11% of incoherently produced events) is described by only four partial waves: the 1+S and 1+P amplitudes, which both show a peak, and the O-S and O-P waves, which are rather constant. We observed variations of both 1+S and 1+P phases relative to the O-P phase by about 90° across the A1 peak. This observation suggests the presence of resonant 1+ waves in the A1 mass region (∼1.1 GeV). In the A3 region we observe that the 2- state shows resonance behaviour and that fπ and ρ{variant}π are two decays modes with amplitudes of opposite signs.
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