Rivet analyses

Drell-Yan dimuon absolute cross-sections in 800 GeV pp and pd collisions

Experiment: NUSEA (Fermilab)

Inspire ID: 613362

Status: VALIDATED

Authors: none listed

References: - FERMILAB-PUB-03-302-E - arXiv: hep-ex/0302019 - J. C. Webb (PhD thesis) hep-ex/0301031

Beams: p+ p+

Beam energies: (19.4, 19.4)GeV

Run details: - Run in pp mode (center-of-mass frame)

The Fermilab E866/NuSea Collaboration has measured the Drell-Yan dimuon cross sections in 800 GeV/c pp and pd collisions. This represents the first measurement of the Drell-Yan cross section in pp collisions over a broad kinematic region and the most extensive study to date of the Drell-Yan cross section in pd collisions. Coded 2003 by Mike Whalley and 2016 by Arathi Ramesh (DESY) using the data tables in hep-ex/0301031.

Source code:NUSEA_2003_I613362.cc

#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DileptonFinder.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/MissingMomentum.hh"

namespace Rivet {


  /// Drell-Yan dimuon absolute cross-sections in 800 GeV pp and pd collisions
  class NUSEA_2003_I613362 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(NUSEA_2003_I613362);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {

      // Projections
      DileptonFinder zfinder(91.2 * GeV, 0.0, Cuts::abseta < 10. && Cuts::abspid == PID::MUON,
                             Cuts::massIn(4.0 * GeV, 100.0 * GeV));
      declare(zfinder, "DileptonFinder");

      // Booking histograms
      // hydrogen d01-d16
      book(_hist_M_xF,
           {-0.05, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8});
      for (auto& b : _hist_M_xF->bins()) {
        book(b, b.index(), 1, 1);
      }

      // deuterium d17-d32

      // hydrogen d40
      book(_hist_pT_M, {4.2, 5.2, 6.2, 7.2, 8.7, 10.85, 12.85});
      _hist_pT_M->maskBin(5);
      int idx = 0;
      for (auto& b : _hist_pT_M->bins()) {
        book(b, 40, 1, ++idx);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {

      // Muons
      const DileptonFinder& zfinder = apply<DileptonFinder>(event, "DileptonFinder");
      if (zfinder.particles().size() <= 0) vetoEvent;

      double Zmass = zfinder.bosons()[0].mom().mass() / GeV;
      double Zpt = zfinder.bosons()[0].mom().pT() / GeV;
      double Zpl = zfinder.bosons()[0].mom().pz() / GeV;
      double ZE = zfinder.bosons()[0].mom().E();
      double xF = 2. * Zpl / sqrtS();

      // Filling dimuon mass in bins of xF
      _hist_M_xF->fill(xF, Zmass / GeV, Zmass * sqr(Zmass));

      // Filling pT in bins of Zmass
      if (xF > -0.05 && xF <= 0.15) {
        // Include here all factors which are run-dependent for later scaling
        if (Zpt > 0) _hist_pT_M->fill(Zmass, Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
      }

      MSG_DEBUG("Dimuon pT = " << Zpt << "   Dimuon E = ");
      MSG_DEBUG("DiMuon mass " << Zmass / GeV);
      MSG_DEBUG("DiMuon pT " << Zpt);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // xf bin width = 0.2, x-section in picobarn
      const double scalefactor = crossSection() / picobarn / (sumOfWeights() * M_PI * 0.2);
      scale(_hist_pT_M, scalefactor);

      // x-section is quoted in nanobarn
      scale(_hist_M_xF, crossSection() / nanobarn / sumOfWeights());

      divByGroupWidth({_hist_pT_M, _hist_M_xF});
    }

    /// @}


  private:

    /// @name Histograms
    /// @{
    Histo1DGroupPtr _hist_pT_M, _hist_M_xF;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(NUSEA_2003_I613362);

}