Consistency tests of rho^0(770)-f_0(980) mixing in pi(-)p->pi(-)pi(+)n
  Analytical solutions of the S-and P-wave subsystem in pi(-)p->pi(-)pi(+)n and pi(+)p->pi(+)pi(-)p measured on polarized targets at CERN reveal evidence for rho^0(770)-f_0(980) spin mixing. We study the response of these analytical solutions to the presence of small D-wave amplitudes with helicity 0,1 (Response analysis A) and helicity 0,1,2 (Response analysis B) which contaminate the input data. In both Response analyses the rho^0(770)-f_0(980) spin mixing effect is clearly consistent with the presence of the D-wave amplitudes provided they are not too large below 750 MeV. We also show that the mixing is consistent with the isospin relations for the S-wave intensities measured in pi(-)p->pi(-)pi(+)n, pi(-)p->pi(0)pi(0)n and pi(+)p->pi(+)pi(+)n processes. These results strengthen the experimental evidence for the rho^0(770)-f_0(980) spin mixing in pi(-)p->pi(-)pi(+)n found in the analytical solutions and are in agreement with recent theoretical expectations. We present a survey of moduli of the S-wave amplitudes and S-wave intensities from all amplitude analyses of the five measurements of pi(-)p->pi(-)pi(+)n and pi(+)n->pi(+)pi(-)p on polarized targets. All analyses are in a remarkable agreement that shows a clear evidence for a resonant structure at rho^0(770) mass in the S-wave moduli and intensities in a broad confirmation of the rho^0(770)-f_0(980) spin mixing. We comment on our recent elastic and joint pipi phase-shift analyses of the CERN pi(-)pi(+) and E852 pi(0)pi(0) data and their agreement with the 1997 and 2002 Cracow Solutions, respectively. Our key observation is that all these solutions for the phase shift delta^0_S are consistent with the evidence for rho^0(770)-f_0(980) mixing documented by our survey. 
Miloslav Svec
hep-ph hep-ex