pi-pi S-Wave Interaction and 0++ Particles
  From a re-analysis of pi+ pi- -> pi+ pi- and pi+ pi- -> K K data, we found for pi-pi S-wave interaction below 2 GeV, sigma(400), f0(980), f0(1500) and f0(1780) clearly show up. f0(1370) can be included with a very small branching ratio to pi-pi. f0(1300) and f0(1590) are not real resonances and are due to interference effects of above resonances. The sigma(400) with a width about 700 MeV is mainly produced by t-channel exchange force. 
B.S. Zou (Queen Mary & Westfield College, London)