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Rivet analyses reference
CDF_2000_S4155203
Z pT measurement in CDF Z -> $e^+e^-$ events
Experiment: CDF (Tevatron Run 1)
Inspire ID: 505738
Status: VALIDATED
Authors:
References:
Beams: p- p+
Beam energies: (900.0, 900.0) GeV
Run details:
- $p\bar{p}$ collisions at 1800 GeV. $Z/\gamma^*$ Drell-Yan events with $e^+e^-$ decay mode only. Restrict $Z/\gamma^*$ mass range to roughly $50 \text{GeV}/c^2 < m_{ee} < 120 \text{GeV}/c^2$ for efficiency.
Measurement of transverse momentum and total cross section of $e^+e^-$ pairs in the Z-boson region of $66 \text{GeV}/c^2 < m_{ee} < 116 \text{GeV}/c^2$ from pbar-p collisions at $\sqrt{s} = 1.8$ TeV, with the Tevatron CDF detector. The $Z$ $p_\perp$, in a fully-factorised picture, is generated by the momentum balance against initial state radiation (ISR) and the primordial/intrinsic $p_\perp$ of the $Z$'s parent partons in the incoming hadrons. The $Z$ $p_\perp$ is important in generator tuning to fix the interplay of ISR and multi-parton interactions (MPI) in generating `underlying event' activity.
This analysis is subject to ambiguities in the experimental Z pT definition, since the Rivet implementation reconstructs the Z momentum from the dilepton pair with finite cones for QED bremstrahlung summation, rather than non-portable direct use of the (sometimes absent) Z in the event record.
Source code:
CDF_2000_S4155203.cc
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68 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ZFinder.hh"
namespace Rivet {
/// @brief CDF Run I Z \f$ p_\perp \f$ in Drell-Yan events
///
/// @author Hendrik Hoeth
class CDF_2000_S4155203 : public Analysis {
public:
RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2000_S4155203);
/// @name Analysis methods
//@{
void init() {
// Set up projections
ZFinder zfinder(FinalState(), Cuts::open(), PID::ELECTRON,
66*GeV, 116*GeV, 0.0, ZFinder::ClusterPhotons::NONE);
declare(zfinder, "ZFinder");
// Book histogram
book(_hist_zpt ,1, 1, 1);
}
/// Do the analysis
void analyze(const Event& e) {
const ZFinder& zfinder = apply<ZFinder>(e, "ZFinder");
if (zfinder.bosons().size() != 1) {
MSG_DEBUG("Num e+ e- pairs found = " << zfinder.bosons().size());
vetoEvent;
}
FourMomentum pZ = zfinder.bosons()[0].momentum();
if (pZ.mass2() < 0) {
MSG_DEBUG("Negative Z mass**2 = " << pZ.mass2()/GeV2 << "!");
vetoEvent;
}
MSG_DEBUG("Dilepton mass = " << pZ.mass()/GeV << " GeV");
MSG_DEBUG("Dilepton pT = " << pZ.pT()/GeV << " GeV");
_hist_zpt->fill(pZ.pT()/GeV);
}
void finalize() {
scale(_hist_zpt, crossSection()/picobarn/sumOfWeights());
}
//@}
private:
Histo1DPtr _hist_zpt;
};
RIVET_DECLARE_ALIASED_PLUGIN(CDF_2000_S4155203, CDF_2000_I505738);
}
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