D-meson production from 400 GeV/c p-p interactions evidence for leading di-quarks

Results of fitting the differential distributions in χF and pT2 of D mesons produced in 400 GeV/c p-p interactions to the form d2σ/dχFdpT2 ∝ (1-xF)n exp[-(pT2/)] are discussed. The D+ distribution is found to be relatively hard [n = 3.1±0.8, = 1.32±0.27 (GeV/c)2] and the anti D0 distribution relatively soft [n = 8.1±1.9, = 0.62±0.14 (GeV/c)2] compared to the average for all D's [n = 4.9±0.5, = 0.99±0.10 (GeV/c)2]. It is suggested that these distributions could reflect the contribution of leading di-quarks in pp collisions. Comparison is made with evidence for leading quarks in charm production in 360 GeV/c π-p interactions. (orig.)