Münster 2011 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 22: Schwerionenkollisionen und QCD Phasen IV

HK 22.5: Talk

Tuesday, March 22, 2011, 17:45–18:00, HS AP

Quark and gluon composition of jets in proton-proton collisions at √s = 7 TeV with ALICE at the LHC — •Hermes Leon Vargas — Institut für Kernphysik, Goethe-Universität Frankfurt am Main

The ALICE experiment at the LHC has excellent tracking capabilities, which makes it an ideal tool to study the properties of charged jets, such as the particle distribution inside the jets. Based on the different fragmentation properties of the jets initiated by quarks or gluons, a method to estimate the ratio of the number of quark over gluon jets as a function of the transverse momentum of the jet is presented. The method is based on the discriminating variable NT90 that allows to statistically differentiate quark and gluon jets. NT90 is defined as the minimum number of tracks, inside the jet cone, necessary to recover 90 % of the jet transverse momentum. A comparison between the predictions of NT90 from the Monte Carlo generators Pythia and Phojet with the measurements performed by ALICE during the recent proton-proton run at √s=7 TeV is presented.