Analysis of the \u3c9\u3c0 12 system produced in the reaction \u3c0 12p\u2192\u3c0 12\u3c0 12\u3c0+\u3c00pat 11.2 GeV/c

The \u3c9\u3c0- mass spectrum, in the reaction \u3c0-p \u2192 \u3c9\u3c0-pat 11.2 GeV/c, shows the production of the B- meson with a cross section of 27 \ub1 5 \u3bcb as well as a clear enhancement around 1670 MeV. In the differential cross section for B- production, there is a strong forward peak and a change of slope at t' t 0.2 GeV2. From the spin-parity decomposition of the \u3c9\u3c0- system, performd using both a standard moments analysis and a partial-wave analysis, we have found that JP = 1+ is the most likely spin-parity assignment for the B-, thus confirming previous results. The spin-density matrix elements, evaluated in the GJ frame, suggest that natural parity exchange dominates the B- production. The \u3c9 helicity-zero contribution is |F01+|2 = 0.06 \ub1 0.04, implying a ratio |CD1+|/|CS1+| = 0.4 \ub1 0.1