Spin and Parity Analysis of BevatronτMesons

Abstract

The data of 71 ${\tau }^{+}$ decays found in emulsions exposed at the Bevatron are presented and analyzed. These data are free from selection bias favoring short-ranged pions. Of these 71 events, 13 have negative pions under 10 Mev and one event has a ${\pi }^{+}$ of (0.38±0.03) Mev. Assuming the distribution functions proposed by Dalitz, the relative probabilities that the 71 events turn out the way they did are 1, ${10}^{-7.9\mathrm{}}$, ${10}^{-33.5\mathrm{}}$, ${10}^{-8.8\mathrm{}}$, ${10}^{-10.5\mathrm{}}$, and <${10}^{-2\mathrm{}}$ for the respective (0-), (1+), (1-), (2+), (3-), and (3+) spin and parity configurations. The (0-) distribution function of Dalitz is statistically a good fit to the data. In addition, 55 Massachusetts Institute of Technology and 100 Berkeley $\tau$ decays are shown to behave essentially the same way. No indication of polarization of the Bevatron $\tau$ beam was found. Conclusions are drawn from the data that the $\tau$ and $\theta$ mesons have different spin-parity configurations and that the only reasonable possibilities for the $\tau$ are (0-) and (2-). The data are also used to give an upper limit for the $s$-wave pion-pion interaction.