Rivet analyses

title: R209_1982_I168182

Drell Yan measurements $pp \to \mu^+\mu^- +X $ at $\sqrt{s} = 44$ and $62$ GeV at CERN ISR

Experiment: R209 (ISR CERN)

Inspire ID: 168182

Status: VALIDATED

Authors: - Hannes Jung

References: - Phys. Rev. Lett., 48(1982), 302 - DOI: 10.1103/PhysRevLett.48.302

Beams: p+ p+

Beam energies: (22.0, 22.0); (31.0, 31.0)GeV

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

Measurements of $pp \to \mu^+\mu^- +X $ at $\sqrt{s} = 44$ and $62$ GeV are compared. The data are #taken under identical conditions utilizing clean proton-proton collisions from the CERN intersecting storage rings and confirm scaling to 5%. Data encoded by Mike Whalley, read from the figure in the paper. Note also, cross sections are quoted in [nb]. The errors shown are statistical only. There is an additional 15% overall systematic uncertainty.

Source code:R209_1982_I168182.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// Drell Yan measurements $pp \to \mu^+\mu^- +X $ at $\sqrt{s} = 44$ and $62$ GeV at CERN ISR class R209_1982_I168182 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(R209_1982_I168182);

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

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

  // Initialise and register projections
  DileptonFinder zfinder(91.2 * GeV, 0.1, Cuts::abseta < 10. && Cuts::abspid == PID::MUON,
                         Cuts::massIn(3.5 * GeV, 18.0 * GeV), LeptonOrigin::PROMPT, PhotonOrigin::NONE);
  declare(zfinder, "DileptonFinder");

  // Book histograms
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    if (en == "44"s) {
      book(_h[en + "M"], 1, 1, 2);
    }
    else {
      book(_h[en + "M"], 1, 1, 1);
      book(_h[en + "pT"], 2, 1, 1);
    }
    const int Nbin = 50;
    book(_n[en + "m"], "DiMuon_mass_" + en, Nbin, 0.0, 30.0);
    book(_n[en + "pT"], "DiMuon_pT_" + en, Nbin, 0.0, 20.0);
    book(_n[en + "y"], "DiMuon_y_" + en, Nbin, -8.0, 8.0);
    book(_n[en + "xF"], "DiMuon_xF_" + en, Nbin, -1.5, 1.5);
  }
  raiseBeamErrorIf(_sqs.empty());
}


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

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

    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 Zy = zfinder.bosons()[0].mom().rap();
    double xf = 2. * Zpl / sqrtS();

    _n[_sqs + "xF"]->fill(xf);
    _n[_sqs + "m"]->fill(Zmass / GeV);
    _n[_sqs + "pT"]->fill(Zpt);
    _n[_sqs + "y"]->fill(Zy);
    if (Zmass > 0) _h[_sqs + "M"]->fill(Zmass);
    if (_sqs == "62"s) {
      if (Zmass > 5. && Zmass < 8.) {
        if (Zpt > 0) _h[_sqs + "pT"]->fill(Zpt, 1.0 / 2.0 / Zpt);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_n);
  scale(_h, crossSection() / nanobarn / sumOfWeights());
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h, _n;
/// @}

/// Energy comparison tolerance
string _sqs = "";

};

RIVET_DECLARE_PLUGIN(R209_1982_I168182);

} ```