Comparison of Hard Scattering Models for Particle Production at Large Transverse Momenta. II. Transverse Momentum and Rapidity Dependence of pi ⁺ and pi ^- Single Particle Distributions

摘要

Single particle distributions of pi ⁺ and pi ^- at large p_ot are analysed using various hard collision models: qq o qq, qoverline q o Moverline M, qM o qM. The p_ot dependence at heta _cm=90^circ is well described in all models except qoverline q o Moverline M. This model has problems with the ratios (pp o pi ⁺+X)/(pp o pi ^-+X) at large x_ot and with (pp o pi ⁰+X)/(pi ^±po pi ⁰+X). Presently available data on rapidity distributions of pions in pi ^-p and poverline p collisions are at rather low p_ot (however large x_ot = 2p_ot sqrt s) where it is not obvious that hard collision models should dominate. The data, in particular the pi ^-/pi ⁺ asymmetry, are well described by all models except qM o Mq (CIM). At large values of p_ot significant differences between the models are predicted.