Robert Steiner

A study of charged final-state hadrons in (pi)(‘+)p, K(‘+)p and pp interactions at a lab energy of 200 GeV/c is presented. Results are based upon a minimum-bias sample of 952 (pi)(‘+)p, 453 K(‘+)p and 1117 pp events acquired with the Fermilab Hybrid Spectrometer. These events are characterized by low transverse momenta (low p(,T)) of the final-state particles. While such processes overwhelmingly dominate the total hadronic cross-section, their underlying dynamics lack a firm theoretical description.

The analysis focuses upon the matrix of reaction channels a + p (—>) c + X where a is the beam particle ((pi)(‘+), K(‘+) or p) and c is one of the charged hadrons (pi)(‘+), (pi)(‘-), K(‘+), K(‘-), p or p. These reactions are studied in terms of the charged hadron fraction, the charged prong topology, and the distribution of transverse momenta of the produced particles. New data on several features of these interactions, particularly the K(‘+)p interactions, is presented. The results are found to be consistent with the predictions of the Lund model for low p(,T) hadroproduction.

In addition, a search was made among the pp interactions for events producing two protons at x(,F) (DBLTURN) 0 among the final-state particles. Speculations based upon the results of previous experiments have suggested that this process may occur with a much higher cross section than would be predicted by the Lund model. No events of the above type have been observed, suggesting an upper limit of production of about 900 (mu)b. This result is consistent with the Lund prediction and imposes serious constraints upon the production of proton pairs at low x(,F).