We study the underlying event in proton-antiproton collisions
by examining the behavior of charged particles (transverse momentum p(t)
> 0.5 GeV/c, pseudorapi+dity |eta| < 1) produced in association
with large transverse momentum jets (~2.2 fb-1) or with Drell-Yan
lepton-pairs (~2.7 fb-1) in the Z-boson mass region (70 < M(pair)
< 110 GeV/c2) as measured by CDF at 1.96 TeV center-of-mass energy.
We use the direction of the lepton-pair (in Drell-Yan production) or the
leading jet (in high-p(t) jet production) in each event to define three
regions of eta-phi space; toward , away, and transverse, where phi is
the azimuthal scattering angle. For Drell-Yan production (excluding the
leptons) both the toward and transverse regions are very sensitive to the
underlying event. In high-p(t) jet production the transverse region is
very sensitive to the underlying event and is separated into a MAX and
MIN transverse region, which helps separate the hard component (initial
and final-state radiation) from the beam-beam remnant and multiple parton
interaction components of the scattering. The data are corrected to
the particle level to remove detector effects and are then compared with
several QCD Monte-Carlo models. The goal of this analysis is to provide
data that can be used to test and improve the QCD Monte-Carlo models of
the underlying event that are used to simulate hadron-hadron collisions.
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Updated: Wednesday, 2010 August 18 13:49:10 CDT automatically from input from Carol Picciolo