  In Part I. of this work we have presented evidence that the measured relative
phases of transversity amplitudes in piN->pipiN processes differ from those
predicted by the unitary evolution law. We ascribed this difference to a
non-unitary interaction of the produced final state rho_f(S) with a universal
quantum environment in the Universe. This new kind of interaction must be a
pure dephasing interaction. If the quantum environment is to be an integral
part of the Nature then its dephasing interactions must be fully consistent
with the Standard Model. In this work we impose on the dephasing interaction
the requirements of the conservation of the identities and four-momenta of the
final state particles, Lorentz symmetry, P-parity and the conservation of total
angular momentum and isospin. From this consistency alone we find that in
piN->pipiN the dephasing interaction must be a dipion spin mixing interaction.
The theory predicts rho^0(770)-f_0(980) mixing in the S- and P-wave amplitudes
in pi(-)p->pi(-)pi(+)n. The predicted moduli and relative phases are in
agreement with experimental results. The spin mixing of S-matrix amplitudes to
form new observable amplitudes is a new phenomenon beyond the Standard Model.
It is our conjecture that the pure dephasing interaction describes the
non-standard interaction of baryonic matter with dark matter and dark energy
which we identify with the quantum environment.

High Energy Physics - Phenomenology;High Energy Physics - Experiment