Measurement of the Production Cross-Section of J/psi Mesons Decaying into Electron-Positron Pairs in Proton-Proton Interactions at a Collision Energy of 10 TeV, using a detailed Simulation of the ATLAS Detector at the CERN LHC

The production of J/psi mesons decaying into electron-positron pairs was studied in simulated proton-proton collisions at 10 TeV using the ATLAS detector at the LHC. The event simulation was performed using the Colour Octet Model for J/psi meson hadroproduction, tuned on previous measurements from the Tevatron. The Colour Octet Model correctly describes the J/psi cross-section at the Tevatron but fails to predict the J/psi polarisation. New measurements of J/psi production need to be performed in order to test the available theoretical models. The p-p collisions delivered by the LHC and recorded by the ATLAS detector will provide data to perform these measurements. Using the silicon and gaseous tracking detectors, combined with electron identification capabilities of the Transition Radiation Tracker, electrons from J/psi decay can be measured in the ATLAS detector. In this thesis, a J/psi cross-section measurement in the electron channel was determined to be feasible, by obtaining the prompt (pp -> J/psi -> ee) and non-prompt (bb -> J/psi -> ee) cross-sections simultaneously. The expected precision of the measurement of the total production cross-sections for p_T^{J/psi} > 10 GeV was evaluated to be sigma_p = 85 ± 4 (stat.) ± 14 (syst.) ± 9 (theo.) nb and sigma_{np} = 20 ± 1 (stat.) ± 4 (syst.) ± 2 (theo.) nb. The differential p_T cross-sections were also studied.