Investigation of resonant π-π interaction in theJ=1,T=1, state

The reaction π−+p→π−+π0+p in the region of small momentum transfer to the proton, has been studied with 1.59 GeV/c pions in a hydrogen bubble chamber. Using the Chew-Low formula as valid in the physical region the elastic cross-section π−-π0 has been calculated. It shows a well-defined peak at 29µ2, the total energy squared in the center of mass of the dipion. On the basis of the angular distribution of the π-π scattering it is demonstrated that the peak is due to a resonant interaction in the stateJ=1, and thereforeT=1.