Seminer Oturumu: "Υ(nS ) Cross Section Measurement in pp collisions at √s = 7 TeV with the CMS Detector" Bora Akgun

Thursday 28 Jun 2012, 18:30 → 20:30 Europe/Zurich

Bora Akgun (Carnegie-Mellon University (US))

The Υ production cross sections are measured with the CMS detector using 36.7 ± 1.5 pb− 1 of proton-proton collisions at √s = 7 TeV. The observed yields of the Υ(1S ), Υ(2S ), and Υ(3S ) reconstructed in the di-muon decay channel are: 73569 ± 465, 23390 ± 364, and 13359 ± 130, respectively. Integrated over the rapidity range |y| ≤ 2.4, the product of the Υ(nS ) production cross section (unpolarized scenario) and the di-muon branching ratio are measured to be σ(pp → Υ(1S )X ) · B(Υ(1S ) → µ + µ−) = 8.347 ± 0.056 (stat.) +0.365 −0.350 (syst.) ± 0.334 (lumi.) nb , σ(pp → Υ(2S )X ) · B(Υ(2S ) → µ + µ−) = 2.274 ± 0.034 (stat.) +0.138 −0.130 (syst.) ± 0.086 (lumi.) nb , σ(pp → Υ(3S )X ) · B(Υ(3S ) → µ + µ−) = 1.175 ± 0.021 (stat.) +0.101 −0.098 (syst.) ± 0.046 (lumi.) nb . where the first uncertainty is statistical, the second is systematic, and the third is associated with the estimation of the integrated luminosity of the data sample. The cross sections are obtained assuming unpolarized-Υ pro- duction. Assuming fully transverse or fully longitudinal polarization leads to variations in the cross sections by about 20%. The Υ(1S ), Υ(2S ), and Υ(3S ) differential cross sections in transverse momentum and rapidity, along with respective cross section ratios, are presented. Comparison to theory predic- tions and previous experimental measurements are provided.

Slides CERNTR.pdf