Production of the Ψ(3100) in 400 GeV Proton - Iron Interactions

The production and subsequent dimuon decay of the vector meson resonance Ψ(3100) have been studied in the collisions of a 400 GeV proton beam incident on an iron target-calorimeter. The apparatus featured a large acceptance iron muon spectrometer, and observed the Ψ over a range of transverse momentum (Pt)from 0 to 4 GeV and of Feynman x (xF) from -.25 to .40 The best fits to the data gave E dσ/dxF ∞ (1 - |xF|)2.96 ± .27 (x2 = 12.9 for 11 degrees of freedom), and 1/Pt dσ/dPt ∞ e-2.23 ± .05 Pt (x2 = 8.6 for 12 degrees of freedom) Pt > 1.2 GeV. The angular distribution of Ψ decays, as measured in the s channel helicity frame, was consistent with a flat spectrum. The observed values of dimuon branching ratio (B) times zero rapidity (y) and total cross sections (B dσ/dy|y=0 and Bσ) were 14.0 ± 2.9 and 22.9 ± 4.7 nanobarns per nucleon respectively. The observed cross sections and differential distributions are presented in the light of existing world data on hadronic Ψ production.