Comparison of hard scattering models for particle production at large transverse momentum. 2

Single particle distributions of π+ and π- at large transverse momentum are analysed using various hard collision models: qq → qq, qantiq → MantiM, qM → qM. The transverse momentum dependence at thetasub(cm) = 900 is well described in all models except qantiq → MantiM. This model has problems with the ratios (pp → π++X)/(π+-p → π0+X). Presently available data on rapidity distributions of pions in π-p and pantip collisions are at rather low transverse momentum (however large xsub(perpendicular) = 2psub(perpendicular)/√s) where it is not obvious that hard collision models should dominate. The data, in particular the π-/π+ asymmetry are well described by all models except qM → Mq (CIM). At large values of transverse momentum significant differences between the models are predicted. (author)