Rivet analyses

title: E605_1991_I302822

Dimuon production in proton-copper collisions at $\sqrt{s} = 38.8$ GeV

Experiment: E605 (Fermilab)

Inspire ID: 302822

Status: VALIDATED

Authors: none listed

References: - Phys. Rev., D43(1991), 2815-2836 - DOI: 10.1103/PhysRevD.43.2815

Beams: p+ p+

Beam energies: (19.4, 19.4)GeV

Run details: none listed

Experimental results on the production of dimuons by 800-GeV protons incident on a copper target are presented. The results include measurements of both the continuum of dimuons and the dimuon decays of the three lowest-mass $\Upsilon$ states.

Source code:E605_1991_I302822.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// Dimuon production in proton-copper collisions at 38.8 GeV class E605_1991_I302822 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(E605_1991_I302822);


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

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

  // Initialise and register projections
  Cut cut = Cuts::abseta < 10.;
  DileptonFinder zfinder(91.2 * GeV, 0.0, cut && Cuts::abspid == PID::MUON,
                         Cuts::massIn(4.0 * GeV, 100.0 * GeV), LeptonOrigin::PROMPT);
  declare(zfinder, "DileptonFinder");

  // Book histograms in mass ranges (measurement is not normalised to mass range)
  book(_h["pT_M_78"], 17, 1, 1);
  book(_h["pT_M_89"], 18, 1, 1);
  book(_h["pT_M_1011"], 19, 1, 1);
  book(_h["pT_M_1113"], 20, 1, 1);
  book(_h["pT_M_1318"], 21, 1, 1);

  int Nbin = 50;
  book(_h_m_DiMuon, "DiMuon_mass", Nbin, 0.0, 30.0);
  book(_h_pT_DiMuon, "DiMuon_pT", Nbin, 0.0, 20.0);
  book(_h_y_DiMuon, "DiMuon_y", Nbin, -8.0, 8.0);
  book(_h_xF_DiMuon, "DiMuon_xF", Nbin, -1.5, 1.5);

  _axis = YODA::Axis<double>(18, 0.0, 3.6);
}


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

  if (_edges.empty()) {
    for (string tag : vector<string>{"pT_M_78", "pT_M_89", "pT_M_1011", "pT_M_1113", "pT_M_1318"}) {
      _edges.insert({tag, _h[tag]->xEdges()});
    }
  }

  const DileptonFinder& zfinder = apply<DileptonFinder>(event, "DileptonFinder");
  if (zfinder.particles().size() >= 1) {

    double Zmass = zfinder.bosons()[0].momentum().mass() / GeV;
    double Zpt = zfinder.bosons()[0].momentum().pT() / GeV;
    double Zpl = zfinder.bosons()[0].momentum().pz() / GeV;
    double Zy = zfinder.bosons()[0].momentum().rapidity();
    double ZE = zfinder.bosons()[0].momentum().E();

    double xf = 2. * Zpl / sqrtS();
    _h_xF_DiMuon->fill(xf);
    _h_m_DiMuon->fill(Zmass / GeV);
    _h_pT_DiMuon->fill(Zpt);
    _h_y_DiMuon->fill(Zy);

    if (xf > -0.1 && xf < 0.2 && Zpt > 0) {
      if (Zmass > 7. && Zmass < 8.) discfill("pT_M_78", Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
      if (Zmass > 8. && Zmass < 9.) discfill("pT_M_89", Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
      if (Zmass > 10.5 && Zmass < 11.5) discfill("pT_M_1011", Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
      if (Zmass > 11.5 && Zmass < 13.5) discfill("pT_M_1113", Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
      if (Zmass > 13.5 && Zmass < 18.) discfill("pT_M_1318", Zpt, 1. / 2. / Zpt * 2. * ZE / sqrtS());
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  MSG_DEBUG(" Generator cross section [pb] " << crossSection() / picobarn);

  normalize(_h_m_DiMuon);
  normalize(_h_pT_DiMuon);
  normalize(_h_xF_DiMuon);
  normalize(_h_y_DiMuon);

  // normalisation of xF bin width = 0.3
  const double scalefactor = crossSection() / picobarn / (sumOfWeights() * M_PI * 0.3);
  scale(_h, scalefactor / 0.2); // divide by bin width
}

/// @}

void discfill(const string& tag, const double value, const double weight) {
  string edge = "OTHER";
  const size_t idx = _axis.index(value);
  if (idx && idx <= _edges.at(tag).size()) {
    edge = _edges.at(tag)[idx - 1];
  }
  _h[tag]->fill(edge, weight);
}

private:

/// @name Histograms
/// @{
Histo1DPtr _h_m_DiMuon;
Histo1DPtr _h_pT_DiMuon;
Histo1DPtr _h_y_DiMuon;
Histo1DPtr _h_xF_DiMuon;
map<string, BinnedHistoPtr<string>> _h;
map<string, vector<string>> _edges;
YODA::Axis<double> _axis;
/// @}

};

RIVET_DECLARE_PLUGIN(E605_1991_I302822);

} ```