Pion-pion effects in τ-decay

Abstract

The effects of pion-pion interactions in resonant form in the s-states of isobaric spins 0 and 2 are studied in some details with respect to the energy and angular distributions of the unlike pion in τ-decay. The relation of the resonance picture with that of the more conventional effective range theory of pion-pion interaction is classified. It is found that the pion-pion hypothesis is capable of explaining the observed distribution in a variety of ways, depending on the choice of the resonance parameters. In particular, an I = 0 interaction is by no means ruled out by experiment. However, on the basis of the present τ-decay data, and in the absence of independent information on the nature of the pion-pion interaction, it is not possible to distinguish between the various alternatives.