  Generalized Bose-Einstein symmetry requires that J+I=even for two-pion
angular states of spin J and total isospin I. We show that the symmetry
predicts three linearly independent constraints on partial wave intensities
with even spin for pi(-)p->pi(-)pi(+)n, pi(-)p->pi(0)pi(0)n and
pi(+)p->pi(+)pi(+)n. Available data violate all three constraints for S, D^0,
D^U and D^N partial waves. The violations of the symmetry imply a presence of
the symmetry violating contributions to transversity amplitudes in
pi(-)p->pi(-)pi(+)n and predict quantum entanglement of pi(-)pi(+) isospin
states which is excluded by the symmetry. We derive approximate lower and upper
bounds on entanglement amplitudes |a_S| and |a_A|. The bounds provide a clear
evidence for entanglement of pi(-)pi(+) isospin states below 840 MeV and
suggest the entanglement at higher dipion masses. The small values of |a_S|
\sim 0.10-0.20 below 840 MeV explain the puzzling differences between the
S-wave intensities in pi(-)p->pi(-)pi(+)n and pi(-)p->pi(0)pi(0)n and reveal a
suppression of isospin I=0,2 contribution in the S-wave amplitudes in
pi(-)p->pi(-)pi(+)n. The large isospin I=1 contribution of rho^0(770) to both
S- and P-wave amplitudes is due to large entanglement amplitude |a_A| \sim
0.98-0.99. These findings confirm the predictions of a model of non-unitary
dynamics of the pion creation processes arising from a CPT violating
interaction of these processes with a quantum environment.
