Υ cross section in p + p collisions at √ s = 200 GeV

Abstract

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)-24+23(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 [sigma]. 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 yield of e+e- pairs from the sum of the Drell-Yan process and b-b̅ production