D-meson production from 400 GeV pp interactions - evidence for leading diquarks?

Results of fitting the differential distributions in x<SUB>F</SUB> and p<SUP>2</SUP><SUB>T</SUB> of D mesons produced in 400 GeV/c p-p interactions to the form d<SUP>2</SUP>σ/dx<SUB>F</SUB>d p<SUP>2</SUP><SUB>T</SUB>α(1-x<SUB>F</SUB>)<SUP>n</SUP> exp[−(p<SUP>2</SUP><SUB>T</SUB>/‹p<SUP>2</SUP><SUB>T</SUB>›)] are discussed. The D<SUP>+</SUP> distribution is found to be relatively hard [n=3.1±0.8≶P<SUB>t</SUB><SUP>2</SUP>≶=1.32±0.27 (GeV/c)<SUP>2</SUP>] and the D<SUP>0</SUP> distribution relatively soft [n=8.1±1.9,≶pT2≶=0.62±0.14 (GeV/c)<SUP>2</SUP>] compared to the average for all D's [n=4.9±0.5,≶p<SUB>T</SUB><SUP>2</SUP>≶=0.99±0.10 (GeV/c)<SUP>2</SUP>]. It is suggested that these distributions could reflect contribution of leading di-quarks in pp collisions. Comparison is made with evidence for leading quarks in charm production in 360 GeV/cπ̅p interactions