Study of charged and neutral multiplicities associated with large transverse momentum π0's in proton-proton collisions

A streamer chamber detector surrounding an intersection region of the CERN ISR was triggered on large transverse momentum π⁰'s by means of an array of lead-glass counters. The directions of all charged particles and photons converted in lead-oxide plates inside the streamer chamber were measured. Data were taken at c.m.s. energies of 45, 53 and 63 GeV around two production angles of the high-p_Tπ⁰ (90° and 53°). The total charged multiplicity associated with large transverse momentum π⁰'s is presented for the first time. Associated photon multiplicities are given for different phase-space regions. The data are compared with two extreme models, a simple jet model and a cluster model which describes normal inelastic events. The cluster model agrees much better with the data.