erable scatter in the estimates of both the cross section for uN-^fN and the/° width. Since we do not wish to discuss or evaluate these discrepancies, we will simply take as a rough guess from the available data that a(7r""/)-*/°n-7r'^7r~"n)~120 /ib at 5 GeV/c (with the same cuts used for the Air data). This gives^ a branching ratioIn order to get a rough idea of the Ul dependence of the cross section we have carried out a similar analysis on the data without a U! cut. We find iVpoo = 69±21 events (all t), in good agreement with the t distribution observed for /° We have not discussed the possibility that the observed peak at 1.27 GeV could be the Z)(1285). We note however that the width and \t\ distribution of our peak are in apparent disagreement with that quoted for the D.^^ We would also require that the spin of the D be ^2.We wish now to comment briefly on the narrow peak at w 47^ ~ 1.42 GeV. The present data are clearly not sufficient to establish the presence of a resonance. If we suppose that the peak is not a statistical fluctuation, the data (Fig. 3) suggest that it may also have J^ = 2"*", and may therefore possibly correspond to the enhancement observed by Beusch et al.^^ in K^^Kj^.

E 7 interval over which the fit is carried out, the cross sections p7r + 7r~ir 0 , whereA N exposure of 1.3X10 6 pictures in the Berkeley 25-in. hydrogen bubble chamber yielded about 57 000 events of the type #-/>-> S+TT-, 2+->^ + neutral, with K~ momenta ranging from 270 to 470 MeV/c. The vast majority of the events were near 390 MeV/c, where the F 0 *(1520) resonance is formed. Of the 48 000 measured events, we were able to identify 61 events of the decay S + -»py.The problem in the experiment was to separate the rare 2+ -> py decays from the more copious X + -> pir 0 decays. 1 The proton momentum in the rest frame of the 2 is 189.0 MeV/c for 2+ -* pir° and 224.6 MeVA for 2+->py. Bazin et al. 2 found a branching ratio of (3.7±0.8)X10~3, using only events with stopped protons. For such events the proton momentum is determined from range rather than curvature, and is thus very accurately known, so that the two decay modes are almost always distinguishable.

An analysis has been made of 51 000 K~ -> 7r~x~7r + decays in flight in the Berkeley 25-in. hydrogen bubble chamber. After corrections for detection efficiency and Coulomb interactions, the projections of the pion spectra have been fitted with expansions in the Dalitz variables X and F. In addition, maximumlikelihood fits to the entire Dalitz plot have been made. The decay distribution is well described by 1+aF, where the slope