Search for diffractive charm production in 800 GeV/c proton-silicon interactions

A search for charm production in the coherent diffractive dissociation reaction pSi→XSi was carried out for the modes D0→K−π+, D0→K−π+π+π−, and D+→K−π+π+. No charm signals were observed, and the 90% confidence level upper limit for coherent charm pair production was determined to be 26 μb per silicon nucleus. The results are interpreted as an upper limit of 0.2% on the amount of intrinsic charm in the proton.