(p)over-barp annihilation into four charged pions at rest and in flight

The spin-parity analysis of the data on the pp → 2π + 2π − annihilation reaction at rest in 50 MeV/c, collected liquid and in gaseous hydrogen at 3 bar pressure and in flight at p momentum of by the Obelix spectrometer at the LEAR complex of CERN, is presented. The relative branching ratios (a1 (1260) → σπ)/(a1 (1260) → ρπ) = 0.06 ± 0.05 and (π(1300) → σπ)/(π(1300) → ρπ) = 2.2 ± 0.4 are obtained. It is also shown that the inclusion of the exotic meson π1 (1400), J P C = 1−+ , mass and width M = 1.384 ± 0.028, Γ = 0.378 ± 0.058 GeV/c2 , in its decay to ρπ, improves the fit and some implications of these results are briefly discussed. The relative S and P -wave annihilation percentages in four charged pions at two target densities are obtained.