STUDY OF PI(+) 2 PI(-) FINAL STATES COHERENTLY PRODUCED ON NUCLEI BY 16 GEV/C PI(-).
Final technical rept.
CALIFORNIA UNIV BERKELEY COSMIC RAY GROUP
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Coherent production of pi 2pi- occurs in approx. 1 of 15 and 16 GeVc pi- C2F5C1 interactions studied in the Ecole Polytechnique HLBC exposed at the CERN P.S.. For nearly every coherent event, one or both pi pi- combinations lies in the rhoo or fo. The ratio of pi- fo to pi- rho o coherent production is 0.05 plus or minus 0.02. No N peaks are seen in the coherent events. S-wave pi- rhoo JP 1 dominates up to at least 1.2 GeV in M pi- rhoo but small admixture of waves of opposite parity is necessary to explain some angular distribution asymmetries. The Dalitz plot excludes dominance of triangle singularity effects. The pi- rhoo mass distribution is dominated by a peak in the A sub 1 region, nearly 250 MeV wide, but too narrow to be explained by the momentum transfer limitation imposed by the nuclear form factor. The calculated OPE Deck model and rho exchange M sub pi rho distributions are also too broad to fit out data, but uncertainties in the model preclude its firm rejection. If M sub pi rho distribution is assumed due entirely to resonances, there must be one dominant JP 1 resonance near 1.05 GeV. To preserve the A sub 1 with width 150 MeV one must assume two other resonances approx 940 and approx 1180 MeV in addition to the A sub 2 1315. Author
- Nuclear Physics and Elementary Particle Physics