Study of the πpi-system with the GAMS-4000 spectrometer at 100 GeV/c

The πpi-system produced in the charge exchange π−p-reaction at 100 GeV/c has been studied. The experiment was performed at the CERN SPS accelerator with the multiphoton hodoscope spectrometer GAMS-4000. A partial wave analysis was carried out in the mass range from 0.8 GeV to 3.0 GeV at −t < 0.2 (GeV/c)2 with the S, D, G and J waves. The S-wave exhibits rather complicated behaviour with a series of four bumps separated by three dips, at 1 GeV, 1.5 GeV and 2 GeV, which give the evidence for several scalar resonances. Clear peaks corresponding to the f2(1270), f4(2050) and f6(2510) mesons are seen in the higher waves. All the three mesons are produced via a dominating one pion t-channel exchange. The parameters and production cross sections of these mesons are measured.