D0_2008_S7837160.cc

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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/Logging.hh"
#include "Rivet/Tools/ParticleIdUtils.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/WFinder.hh"
#include "Rivet/Projections/LeadingParticlesFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/RivetAIDA.hh"

#include "LWH/Histogram1D.h"
#include "LWH/HistogramFactory.h"

namespace Rivet {


  /// @brief Measurement of W charge asymmetry from D0 Run II
  /// @author Andy Buckley
  /// @author Gavin Hesketh
  class D0_2008_S7837160 : public Analysis {

  public:

    /// Default constructor.
    D0_2008_S7837160()
      : Analysis("D0_2008_S7837160")
    {
      // Run II W charge asymmetry
      setBeams(PROTON, ANTIPROTON);
    }
 
 
    /// @name Analysis methods
    //@{
 
    // Book histograms and set up projections
    void init() {
      // Projections
      /// @todo Use separate pT and ETmiss cuts in WFinder
      const WFinder wfe(-5, 5, 0.0*GeV, ELECTRON, 60.0*GeV, 100.0*GeV, 0*GeV, 0.2);
      addProjection(wfe, "WFe");

      // Cross-section histograms
      const BinEdges& edges = binEdges(1,1,1);
      _h_dsigplus_deta_25_35  = bookHistogram1D("/dsigplus_deta_25_35", edges);
      _h_dsigminus_deta_25_35 = bookHistogram1D("/dsigminus_deta_25_35", edges);
      _h_dsigplus_deta_35     = bookHistogram1D("/dsigplus_deta_35", edges);
      _h_dsigminus_deta_35    = bookHistogram1D("/dsigminus_deta_35", edges);
      _h_dsigplus_deta_25     = bookHistogram1D("/dsigplus_deta_25", edges);
      _h_dsigminus_deta_25    = bookHistogram1D("/dsigminus_deta_25", edges);
    }

 
    /// Do the analysis
    void analyze(const Event & event) {
      const WFinder& wf = applyProjection<WFinder>(event, "WFe");
      if (wf.size() == 0) {
        getLog() << Log::DEBUG << "No W candidates found: vetoing" << endl;
        vetoEvent;
      }

      // Require that leptons have Et >= 25 GeV
      /// @todo Use pT cut in WFinder
      /// @todo Any ETmiss cut?
      FourMomentum p_e;
      int chg_e = 0;
      foreach (const Particle& l, wf.constituentsFinalState().particles()) {
        const FourMomentum pl = l.momentum();
        if (abs(l.pdgId()) == ELECTRON) {
          chg_e = PID::threeCharge(l.pdgId());
          p_e = pl;
        }
        if (pl.Et()/GeV < 25.0) {
          getLog() << Log::DEBUG << l.pdgId() << " fails Et cut" << endl;
          vetoEvent;
        }
      }
      assert(chg_e != 0);
      
      const double weight = event.weight();
      const double eta_e = fabs(p_e.pseudorapidity());
      const double et_e = p_e.Et();
      if (et_e < 35*GeV) {
        // 25 <= ET < 35
        if (chg_e < 0) {
          _h_dsigminus_deta_25_35->fill(eta_e, weight);
        } else {
          _h_dsigplus_deta_25_35->fill(eta_e, weight);
        }
      } else {
        // ET >= 35
        if (chg_e < 0) {
          _h_dsigminus_deta_35->fill(eta_e, weight);
        } else {
          _h_dsigplus_deta_35->fill(eta_e, weight);
        }
      }
      // Inclusive: ET >= 25
      if (chg_e < 0) {
        _h_dsigminus_deta_25->fill(eta_e, weight);
      } else {
        _h_dsigplus_deta_25->fill(eta_e, weight);
      }
    }


    /// Finalize
    void finalize() {
      // Construct asymmetry: (dsig+/deta - dsig-/deta) / (dsig+/deta + dsig-/deta) for each Et region
      AIDA::IHistogramFactory& hf = histogramFactory();
   
      IHistogram1D* num25_35 = hf.subtract("/num25_35", *_h_dsigplus_deta_25_35, *_h_dsigminus_deta_25_35);
      IHistogram1D* denom25_35 = hf.add("/denom25_35", *_h_dsigplus_deta_25_35, *_h_dsigminus_deta_25_35);
      assert(num25_35 && denom25_35);
      hf.divide(histoDir() + "/d01-x01-y01", *num25_35, *denom25_35);
      hf.destroy(num25_35);
      hf.destroy(denom25_35);
      //
      IHistogram1D* num35 = hf.subtract("/num35", *_h_dsigplus_deta_35, *_h_dsigminus_deta_35);
      IHistogram1D* denom35 = hf.add("/denom35", *_h_dsigplus_deta_35, *_h_dsigminus_deta_35);
      assert(num35 && denom35);
      hf.divide(histoDir() + "/d01-x01-y02", *num35, *denom35);
      hf.destroy(num35);
      hf.destroy(denom35);
      //
      IHistogram1D* num25 = hf.subtract("/num25", *_h_dsigplus_deta_25, *_h_dsigminus_deta_25);
      IHistogram1D* denom25 = hf.add("/denom25", *_h_dsigplus_deta_25, *_h_dsigminus_deta_25);
      assert(num25 && denom25);
      hf.divide(histoDir() + "/d01-x01-y03", *num25, *denom25);
      hf.destroy(num25);
      hf.destroy(denom25);

      // Delete raw histos
      hf.destroy(_h_dsigplus_deta_25_35);
      hf.destroy(_h_dsigminus_deta_25_35);
      hf.destroy(_h_dsigplus_deta_35);
      hf.destroy(_h_dsigminus_deta_35);
      hf.destroy(_h_dsigplus_deta_25);
      hf.destroy(_h_dsigminus_deta_25);
    }
 
    //@}


  private:

    /// @name Histograms
    //@{
    AIDA::IHistogram1D *_h_dsigplus_deta_25_35, *_h_dsigminus_deta_25_35;
    AIDA::IHistogram1D *_h_dsigplus_deta_35, *_h_dsigminus_deta_35;
    AIDA::IHistogram1D *_h_dsigplus_deta_25, *_h_dsigminus_deta_25;
    //@}

  };


  // This global object acts as a hook for the plugin system
  AnalysisBuilder<D0_2008_S7837160> plugin_D0_2008_S7837160;

}