Rivet analyses

Drell Yan measurements $pp +- +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 +- +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++ -*-
#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);

}