A search for narrow resonances in proton-proton collisions

The magnetic spectrometer used in R803 (and R413) was used in conjunction with another magnetic spectrometer at a small angle with respect to the ISR beam as shown in figure 1. The combined apparatus measured and indentified two final state charged hadrons. A mass resolution of 10-20 MeV in the invariant mass was abotained.

Figure 1

Sketch of the apparatus showing the Small Angle Spectrometer (SAS) positioned above the downstream arm of one of the beams, and the Wide Angle Spectrometer (WAS) positioned in the plane defined by the two proton beams. S2, BM1, BM2, BM3, and BMw indicate magnets, C1 , C2, C3, Clw, and C2w. indicate gas Cerenkov counters.

During the year the analysis of this experiment has been completed. Correlation functions were determined for various combinations of particles. The two-particle invariant mass spectra show no strong structure suggesting the presence of a new narrow resonance. The statistical significance of various enhancements, such as K~p at 2150 MeV and a bump with baryon number 1 at 3510 MeV seen in the data, is not convincing and upper limits on the cross-section times branching ratio for new particle production are given.