München 2009 – scientific programme

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T: Fachverband Teilchenphysik

T 30: QCD 4

T 30.2: Talk

Friday, March 13, 2009, 14:15–14:30, A017

Using Drell-Yan to Probe the Underlying Event in Run 2 at CDF — •Deepak Kar — Institut für Kern- und Teilchenphysik, TU Dresden, D-01062 Dresden — on behalf of the CDF Collaboration

We study the behavior of charged particles produced in association with Drell-Yan lepton-pairs in the region of the Z-boson (70 < M(pair) < 110 GeV/c²) in proton-antiproton collisions at √s=1.96 TeV. We use the direction of the Z-boson in each event to define three regions of η−φ space; ‘toward’, ‘away’, and ‘transverse’. For Drell-Yan production (excluding the leptons) both the ‘toward’ and ‘transverse’ regions are very sensitive to the ‘underlying event’. The data are corrected to the particle level and are then compared with several PYTHIA models (with multiple parton interactions) and HERWIG (without multiple parton interactions) at the particle level. The data are also compared with a previous analysis on the behavior of the "underlying event" in high transverse momentum jet production. Further, we look at the rate of change of average transverse momentum versus the charged multiplicity, which is a measure of the amount of hard versus soft processes contributing and it is sensitive to the modeling of the multiple-parton interactions. The goal is to improve our understanding and modeling of high energy collider events to allow for more precise predictions at the LHC.