Observation of diffraction excitation in pp → (pπ+π−)+X at the CERN-ISR and tests of limiting fragmentation

Abstract In a single-arm magnetic spectrometer experiment at the CERN Intersecting Storage Rings (ISR), a prominent diffractive enhancement is observed for inclusive production of (p π + π − ) systems near x ∼ 1 at √s = 53 and 35 GeV. In testing limiting fragmentation and scaling for this system, inclusive p π + π − diffractive excitation into a fixed invariant mass range is found to possess a cross-section independent of s to within (3 ± 5)%. The main component in the (p π + π − ) system is Δ (1236) π , with a charge structure compatible with the break-up of an isotopic spin 1 2 system.