The role of valence quarks in proton fragmentation

Following earlier theoretical and experimental work baryon production by fragmentation of incident protons in high energy hadron collisions is re-investigated in terms of a fragmentation-recombination mechanism similar to a model proposed by Fukuda and Iso. The multiplicities nsub(f)(B) for the various types of baryons B produced in proton fragmentation are expressed in terms of the probabilities asub(i) for i = 0,.....3 valence quarks of the incident proton to emerge in the baryon B and 3-i to emerge in mesons (we suppose that antibaryon production is mostly due to baryon-antibaryon pair production by a mechanism of non-fragmentation type, and this is taken into a account in deducing nsub(f)(B) from baryon and antibaryon multiplicity data). The positivity of the asub(i) is found to impose remarkably narrow constraints on the nsub(f)(B) for (meta)stable B, and we find the data to satisfy these constraints. We show furthermore that the data are compatible with uncorrelated behaviour of the valence quarks of the incident proton, each of them having a probability approx. equal to 0.6 to emerge in the fragmentation baryon B, and a probability approx. equal to 0.4 to emerge in a meson. We also briefly discuss the relation of our analysis to previous work on the recombination model of proton fragmentation and its possible extension to meson fragmentation. (orig.)