Hadroproduction of the {chi}{sub 1} and {chi}{sub 2} states of charmonium in 800-GeV/c proton-silicon interactions

The cross sections for the hadroproduction of the {chi}{sub 1} and {chi}{sub 2} states of charmonium in proton-silicon collisions at {radical}(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{sup +}e{sup -} in the material of the spectrometer. The estimated values for the {chi}{sub 1} and {chi}{sub 2} cross sections for x{sub F}>0 are 263{+-}69(stat){+-}32(syst) and 498{+-}143(stat){+-}67(syst) nb per nucleon, respectively. The resulting {sigma}({chi}{sub 1})/{sigma}({chi}{sub 2}) ratio of 0.53{+-}0.20(stat){+-}0.07(syst), although somewhat larger than most theoretical expectations, can be accommodated by the latest theoretical estimates. (c) 2000 The American Physical Society.