Cross-Section Measurements for Charm Production by 209-GeV Muons

Interactions of 209-GeV muons in the Multimuon Spectrometer at Fermilab have yielded 20072 dimuon final states, with (81±10)% attributed to production of charmed states decaying to muons. The cross section for diffractive charm muoproduction is 6.9{sub -1.4}{sup +1.9} nb. Extrapolated to Q{sup 2} =0, the effective cross section for 178(100)-GeV photons is 750{sup +180}{sub -130} (560{sup +200}{sub -130}) nb, too small to explain the high-energy rise in the photon-nucleon total cross section.