M ay 2 01 0 Υ cross section in p + p collisions at √ s = 200 GeV
نویسندگان
چکیده
We report on a measurement of the Υ(1S+2S+3S) → e + e − cross section at midrapidity in p + p collisions at √ s = 200 GeV. We find the cross section to be 114 ± 38 (stat. + fit) +23 −24 (syst.) pb. Perturbative QCD calculations at next-to-leading order in the Color Evaporation Model are in agreement with our measurement, while calculations in the Color Singlet Model underestimate it by 2σ. Our result is consistent with the trend seen in world data as a function of the center-of-mass energy of the collision and extends the availability of Υ data to RHIC energies. The dielectron continuum in the invariant mass range near the Υ is also studied to obtain a combined cross section of Drell-Yan plus b-¯ b → e + e − .
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