Associated multiplicities in proton-proton collisions with a charged hadron at X=0 at the CERN ISR

Charged-particle multiplicities and angular distributions associated with a pi /sup +or-/, K/sup +or-/, p and p produced at 90 degrees , have been measured at the CERN ISR. The triggering particle was identified by a magnetic spectrometer, within a range of transverse laboratory momentum p/sub T/ which was different for different particles. Associated multiplicities have been obtained as a function of p/sub T/ at the different ISR beam energies. The distributions of the associated particles have been studied as functions of the azimuthal angle phi and of the pseudorapidity eta . In the high-p/sub T/ region associated multiplicities increase for all particle types approximately linearly with p/sub T/. The momentum of a high-p/sub T/ particle is seen to be balanced over a wide cone of phi and eta in the opposite hemisphere. An increase in the multiplicities of secondaries in the same hemisphere near the triggering particle is also observed for the high p/sub T/ baryons. At low p/sub T/ there is an increase in associated multiplicity on the same side as the transverse momentum of the pion approaches zero. (9 refs).