Transverse momentum distribution in Pomeron-Pomeron collisions at the CERN ISR

Proton-proton interactions which result in a central cluster of massM x and two quasi-elastically scattered protons are generally described by Pomeron-Pomeron scattering. A study of this process at ISR energies with the Split Field Magnet detector is carried out in terms of transverse momentum behaviour for the centrally produced system of particles. The inclusivep T distribution for central hadrons is measured up to 3 GeV/c. Forp T <1.2 GeV/c, thep T distribution is exponential. Using a subsample of exclusive events, this exponential shape is shown to originate from a phase-space-like decay ofM x when convoluted with a transverse component of the pomeron momentum. In the highp T range, the shape of thep T distribution strongly depends on Feynman-x of the scattered protons in a way that can be described by hard parton scattering.