Measurement of the φφ cross section in p annihilations at ECM≈3 GeV

M ay 2 01 0 Υ cross section in p + p collisions at √ s = 200 GeV

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 ...

gamma cross section in p plus p collisions at root s=200 GeV

Measurement of the Open Charm Cross-section in 200 Gev Heavy-ion Collisions at Star

Theory predicts that charm quarks are produced by initial gluon fusion during the very early stages of the matter produced in a relativistic heavyion collision. These gluon fusion reactions occur through high momentum transfer (Q) processes before the thermalization of the collision fireball [1]. Gluon fusion reactions scale with the number of binary (nucleon-nucleon) collisions, allowing us to...

The Ratio of the Direct Photon Production Cross Section at 630 GeV and at 1800 GeV

We measure the ratio of the isolated direct photon prodution cross section at √ s = 630 GeV to that at √ s = 1800 GeV for the central (|η| < 0.9) and forward (1.6 < |η| < 2.5) rapidity regions. We compare the result with next to leading order QCD predictions using CTEQ parton distribution functions.

Measurement of the total cross section for e+e-âƒTMhadrons at â‹ıs=10.52 GeV