POSITIVE PARTICLE PRODUCTION AT LARGE TRANSVERSE MOMENTA IN THE FRAGMENTATION REGION (P 342)

A striking feature of particle production at the CERN ISR has been the observation [1,7] that at high pT the distribution of secondary particles produced in the central region deviates from the exponential fall-off characteristic of low pT data and begins to flatten out. It has been argued, initially by Berman, Bjorken and Kogut [2], that such behaviour may be considered as evidence for point-like constituents inside the proton. An alternative interpretation [3] would be to relate the secondaries produced at high pT with the decay of massive "fireballs", apparently produced with significant cross-section a t ISR energies [4]. In either case one would also expect an excess of high pT particles away from the central region. In this letter we report measurements of π+, K+ and proton production cross-sections in the fragmentation region at x = 0.6 for a range of pT from 0.33 GeV to 2.55 GeV