Measurement of the cross section ratio σ(χc₂)/σ(χc₁) for prompt χc production with CMS experiment

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Thesis Type: Doctorate

Institution Of The Thesis: Middle East Technical University, Turkey

Approval Date: 2012

Thesis Language: English

Student: Ilina Vasileva Akin

Supervisor: MEHMET TEVFİK ZEYREK

Abstract:

The prompt production of χc quarkonia is studied in proton-proton collisions at 7 TeV, using data collected by CMS in 2011 corresponding to an integrated luminosity of 4.6 fb −1. The χc mesons are reconstructed through their radiative decays to J/ψ and photon with J/ψ → μ+μ− . The photons are reconstructed through their conversion in electron-positron pairs in the tracking detector which gives a mass resolution sufficient for resolving these states. The ratio of the prompt production ₁cross sections for the χc1 and χc2 states, σ(χc2)/σ(χc1), has been determined as a function of the J/ψ transverse momentum between 7 and 25 GeV/c.