Münster 2011 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 40: Schwerionenkollisionen und QCD Phasen V

HK 40.9: Talk

Wednesday, March 23, 2011, 18:30–18:45, HS AP

Underlying Event measurement in pp collisions with the ALICE detector — •Sara Vallero for the ALICE collaboration — Physikalisches Institut , University of Heidelberg

In a hadronic machine a clear jet signature has to be decoupled from the soft or semi-hard bulk of particles originating from beam remnant fragmentation, initial and final state radiation and multi-partonic interactions: the so-called Underlying Event. We studied the underlying activity in two transverse regions azimuthally perpendicular to the leading track in the event. Only charged particles are considered. This characterization provides a baseline for jet studies as well as a closer look into the non-perturbative phenomenology in high energy hadronic collisions and, in particular, it serves as a powerful tool to tune Monte-Carlo event generators. In this talk we describe the correction procedure applied to experimental data in order to eliminate detector-related biases and inefficiencies. Moreover, we summarize the determination of the systematic uncertainties affecting the correction procedure. Finally, we present the fully corrected Underlying Event distributions for pp interactions at collision energies of 900 GeV and 7 TeV.