  Recently a strong indication for a deviation from the standard model (SM) has
been obtained by PIBETA Collaboration. Namely, SM fails to describe the energy
distribution and the branching ratio of the radiative decays of the positive
pions at rest in the high-E_gamma/low-E_e kinematic region.
  The previous experiment at ISTRA facility, testing the radiative decays of
negative pions in flight in a wide kinematic region has alarmed about the same
effect, although statistically less significant. The present PIBETA result
indicates a deficit of the branching ratio of the radiative pion decay in the
specified kinematic region at 8 sigma level in comparison with SM prediction,
while in the other kinematic regions both the branching ratios and the energy
distributions are compatible with the V-A interaction.
  We argue that this effect can result only from a small admixture of new
tensor interactions. They may arise due to an exchange of new spin one chiral
bosons which interact anomalously with matter.
