The cross sections for the hadroproduction of the Chi1 and Chi2 states of charmonium in proton-silicon collisions at sqrt{s}=38.8 GeV have been measured in Fermilab fixed target Experiment 771. The Chi states were observed via their radiative decay to J/psi+gamma, where the photon converted to e+e- in the material of the spectrometer. The measured values for the Chi1 and Chi2 cross sections for x_F>0 are 263+-69(stat)+-32(syst) and 498+-143(stat)+-67(syst) nb per nucleon respectively. The resulting sigma(Chi1}/sigma(Chi2) ratio of 0.53+-0.20(stat)+-0.07(syst), although somewhat larger than most theoretical expectations, can be accomodated by the latest theoretical estimates.
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The production of the χ1 and χ2 states of charmonium has been observed in 300 GeV/c π±N and pN interactions. The fraction of the total inclusive J/ψ production due to radiative χ decay has been determined to be 0.40±0.04, 0.37±0.03, and 0.30±0.04 for the π+, π−, and proton data, respectively. Total cross sections have been obtained of 131±18±14 and 188±30±21 nb/nucleon in the 300 GeV/c π−N interactions for χ1 and χ2 production. By measuring the contributions to the J/ψ production due to both ψ’ and radiative χ decay, the cross sections for direct J/ψ production have been determined to be 97±14, 102±14, and 89±12 nb/nucleon for π+, π−, and protons, respectively.
Fractions of total J/PSI production due to radiative CHI1 and CHI2 decays.
Fractions of total J/PSI production due to radiative CHI1 and CHI2 decays.
Fractions of total J/PSI production due to radiative CHI1 and CHI2 decays.