Rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

CDF_2010_S8591881_QCD

CDF Run 2 underlying event in leading jet events
Experiment: CDF (Tevatron Run 2)
Inspire ID: 849042
Status: VALIDATED
Authors:
  • Hendrik Hoeth
References:
  • Phys.Rev.D82:034001,2010
Beams: p- p+
Beam energies: (980.0, 980.0) GeV
Run details:
  • $p\bar{p}$ QCD interactions at 1960 GeV. Particles with $c \tau > {}$10 mm should be set stable. Several $p_\perp^\text{min}$ cutoffs are probably required to fill the profile histograms. $p_\perp^\text{min} = {}$ 0 (min bias), 10, 20, 50, 100, 150 GeV. The corresponding merging points are at $p_T = $ 0, 30, 50, 80, 130, 180 GeV

Rick Field's measurement of the underlying event in leading jet events. If the leading jet of the event is within $|\eta| < 2$, the event is accepted and ``toward'', ``away'' and ``transverse'' regions are defined in the same way as in the original (2001) CDF underlying event analysis. The leading jet defines the $\phi$ direction of the toward region. The transverse regions are most sensitive to the underlying event.

Source code: CDF_2010_S8591881_QCD.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {


  /// @brief CDF Run II underlying event in leading jet events
  /// @author Hendrik Hoeth
  ///
  /// Rick Field's measurement of the underlying event in "leading jet" events.
  /// The leading jet (CDF midpoint \f$ R = 0.7 \f$) must be within \f$|\eta| < 2 \f$
  /// and defines the "toward" phi direction. Particles are selected in
  /// \f$ |\eta| < 1 \f$. For the \f$ p_\perp \f$-related observables there
  /// is a \f$ p_\perp > 0.5 \f$ GeV cut. For \f$ \sum E_\perp \f$ there is no
  /// \f$ p_\perp \f$ cut.
  ///
  /// @par Run conditions
  /// @arg \f$ \sqrt{s} = \f$ 1960 GeV
  /// @arg Run with generic QCD events.
  /// @arg Set particles with c*tau > 10 mm stable
  /// @arg Several \f$ p_\perp^\text{min} \f$ cutoffs are probably required to fill the profile histograms:
  /// @arg \f$ p_\perp^\text{min} = \f$ 0 (min bias), 10, 20, 50, 100, 150 GeV
  /// @arg The corresponding merging points are at \f$ p_T = \f$ 0, 30, 50, 80, 130, 180 GeV
  class CDF_2010_S8591881_QCD : public Analysis {
  public:

    /// Constructor
    CDF_2010_S8591881_QCD()
      : Analysis("CDF_2010_S8591881_QCD")
    {
    }


    /// @name Analysis methods
    //@{

    void init() {
      // Final state for the jet finding
      const FinalState fsj(-4.0, 4.0, 0.0*GeV);
      declare(fsj, "FSJ");
      declare(FastJets(fsj, FastJets::CDFMIDPOINT, 0.7), "MidpointJets");

      // Charged final state for the distributions
      const ChargedFinalState cfs(-1.0, 1.0, 0.5*GeV);
      declare(cfs, "CFS");

      // Book histograms
      _hist_tnchg      = bookProfile1D(10, 1, 1);
      _hist_pnchg      = bookProfile1D(10, 1, 2);
      _hist_anchg      = bookProfile1D(10, 1, 3);
      _hist_pmaxnchg   = bookProfile1D(11, 1, 1);
      _hist_pminnchg   = bookProfile1D(11, 1, 2);
      _hist_pdifnchg   = bookProfile1D(11, 1, 3);
      _hist_tcptsum    = bookProfile1D(12, 1, 1);
      _hist_pcptsum    = bookProfile1D(12, 1, 2);
      _hist_acptsum    = bookProfile1D(12, 1, 3);
      _hist_pmaxcptsum = bookProfile1D(13, 1, 1);
      _hist_pmincptsum = bookProfile1D(13, 1, 2);
      _hist_pdifcptsum = bookProfile1D(13, 1, 3);
      _hist_pcptave    = bookProfile1D(14, 1, 1);
      _hist_pcptmax    = bookProfile1D(15, 1, 1);
    }


    // Do the analysis
    void analyze(const Event& e) {
      /// @todo Implement Run II min bias trigger cf. CDF_2009?

      const FinalState& fsj = apply<FinalState>(e, "FSJ");
      if (fsj.particles().size() < 1) {
        MSG_DEBUG("Failed multiplicity cut");
        vetoEvent;
      }

      const Jets& jets = apply<FastJets>(e, "MidpointJets").jetsByPt();
      MSG_DEBUG("Jet multiplicity = " << jets.size());

      // We require the leading jet to be within |eta|<2
      if (jets.size() < 1 || fabs(jets[0].eta()) >= 2) {
        MSG_DEBUG("Failed leading jet cut");
        vetoEvent;
      }

      const double jetphi = jets[0].phi();
      const double jeteta = jets[0].eta();
      const double jetpT  = jets[0].pT();
      MSG_DEBUG("Leading jet: pT = " << jetpT
                << ", eta = " << jeteta << ", phi = " << jetphi);

      // Get the event weight
      const double weight = e.weight();

      // Get the final states to work with for filling the distributions
      const FinalState& cfs = apply<ChargedFinalState>(e, "CFS");

      size_t numOverall(0),     numToward(0),          numAway(0)  ;
      long int numTrans1(0),     numTrans2(0);
      double ptSumOverall(0.0), ptSumToward(0.0), ptSumTrans1(0.0), ptSumTrans2(0.0), ptSumAway(0.0);
      double ptMaxOverall(0.0), ptMaxToward(0.0), ptMaxTrans1(0.0), ptMaxTrans2(0.0), ptMaxAway(0.0);

      // Calculate all the charged stuff
      foreach (const Particle& p, cfs.particles()) {
        const double dPhi = deltaPhi(p.phi(), jetphi);
        const double pT = p.pT();
        const double phi = p.phi();
        double rotatedphi = phi - jetphi;
        while (rotatedphi < 0) rotatedphi += 2*PI;

        ptSumOverall += pT;
        ++numOverall;
        if (pT > ptMaxOverall) {
          ptMaxOverall = pT;
        }

        if (dPhi < PI/3.0) {
          ptSumToward += pT;
          ++numToward;
          if (pT > ptMaxToward) ptMaxToward = pT;
        }
        else if (dPhi < 2*PI/3.0) {
          if (rotatedphi <= PI) {
            ptSumTrans1 += pT;
            ++numTrans1;
            if (pT > ptMaxTrans1) ptMaxTrans1 = pT;
          } else {
            ptSumTrans2 += pT;
            ++numTrans2;
            if (pT > ptMaxTrans2) ptMaxTrans2 = pT;
          }
        }
        else {
          ptSumAway += pT;
          ++numAway;
          if (pT > ptMaxAway) ptMaxAway = pT;
        }
      } // end charged particle loop

      // Fill the histograms
      _hist_tnchg->fill(jetpT/GeV, numToward/(4*PI/3), weight);
      _hist_pnchg->fill(jetpT/GeV, (numTrans1+numTrans2)/(4*PI/3), weight);
      _hist_pmaxnchg->fill(jetpT/GeV, (numTrans1>numTrans2 ? numTrans1 : numTrans2)/(2*PI/3), weight);
      _hist_pminnchg->fill(jetpT/GeV, (numTrans1<numTrans2 ? numTrans1 : numTrans2)/(2*PI/3), weight);
      _hist_pdifnchg->fill(jetpT/GeV, abs(numTrans1-numTrans2)/(2*PI/3), weight);
      _hist_anchg->fill(jetpT/GeV, numAway/(4*PI/3), weight);

      _hist_tcptsum->fill(jetpT/GeV, ptSumToward/GeV/(4*PI/3), weight);
      _hist_pcptsum->fill(jetpT/GeV, (ptSumTrans1+ptSumTrans2)/GeV/(4*PI/3), weight);
      _hist_pmaxcptsum->fill(jetpT/GeV, (ptSumTrans1>ptSumTrans2 ? ptSumTrans1 : ptSumTrans2)/GeV/(2*PI/3), weight);
      _hist_pmincptsum->fill(jetpT/GeV, (ptSumTrans1<ptSumTrans2 ? ptSumTrans1 : ptSumTrans2)/GeV/(2*PI/3), weight);
      _hist_pdifcptsum->fill(jetpT/GeV, fabs(ptSumTrans1-ptSumTrans2)/GeV/(2*PI/3), weight);
      _hist_acptsum->fill(jetpT/GeV, ptSumAway/GeV/(4*PI/3), weight);

      if ((numTrans1+numTrans2) > 0) {
        _hist_pcptave->fill(jetpT/GeV, (ptSumTrans1+ptSumTrans2)/GeV/(numTrans1+numTrans2), weight);
        _hist_pcptmax->fill(jetpT/GeV, (ptMaxTrans1 > ptMaxTrans2 ? ptMaxTrans1 : ptMaxTrans2)/GeV, weight);
      }
    }


    void finalize() {
    }

    //@}


  private:

    Profile1DPtr _hist_tnchg;
    Profile1DPtr _hist_pnchg;
    Profile1DPtr _hist_anchg;
    Profile1DPtr _hist_pmaxnchg;
    Profile1DPtr _hist_pminnchg;
    Profile1DPtr _hist_pdifnchg;
    Profile1DPtr _hist_tcptsum;
    Profile1DPtr _hist_pcptsum;
    Profile1DPtr _hist_acptsum;
    Profile1DPtr _hist_pmaxcptsum;
    Profile1DPtr _hist_pmincptsum;
    Profile1DPtr _hist_pdifcptsum;
    Profile1DPtr _hist_pcptave;
    Profile1DPtr _hist_pcptmax;

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CDF_2010_S8591881_QCD);

}