New interactions in the radiative pion decay

The preliminary results of PIBETA experiment strongly suggest the presence of non V-A anomalous interactions in the radiative pion decay. Without a guiding idea about the nature of these new interactions it is very difficult to interpret and fit experimental data. We assume that they arise as a result of the exchange of new intermediate chiral bosons which interact anomalously with matter. Their mixing with W-bosons leads effectively to a small anomalous weak moment for W. Based on these assumptions, we show that the most general form of the radiative pion decay rate can be parametrized by three new coupling constants of the anomalous interactions.