Angular dependence of high-p/sub T/ pi /sup 0/ production

The authors have measured inclusive pi /sup 0/ production cross- sections at the CERN ISR for p/sub T/ <5 GeV/c at c.m. angles of theta =90 degrees and 5< theta <22 degrees at c.m. energies square root s=23 and 53 GeV. The data are in agreement with previous measurements of pi degrees production at FNAL and the ISR. The authors have compared these data with the hypothesis of radial scaling, which asserts that the inclusive cross section should be a function of x/sub R/ and p/sub T/ alone. Here x/sub R/ is the fraction of available energy carried by the produced particle. They find that radial scaling is not satisfactory over the energy and angle range of this experiment. Comparing their data with radial scaling fits to mainly FNAL data, the authors find that their cross sections approach ten times the prediction at large p/sub T/ and x/sub R/. As a more direct test of the hypothesis, the authors compare their data for which x/sub R/ variation occurs as theta varies at fixed s, with that from ISR experiments at fixed theta =90 degrees and variable s. The trend of the two data sets is in marked disagreement. The authors have also compared their results with predictions from a QCD-based model. The angular distribution at fixed p/sub T/ is well described by the model. The results described here are more fully discussed in a recent publication (see Phys. Rev. Lett., vol.45, no.2, p.89-93, 1980). (1 refs).