Rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

ATLAS_2012_I1190891

4 or more lepton plus missing transverse energy SUSY search
Experiment: ATLAS (LHC)
Inspire ID: 1190891
Status: UNVALIDATED
Authors:
  • Peter Richardson
References:
  • ATLAS-CONF-2012-001
  • ATLAS-CONF-2012-035
  • arXiv: 1210.4457
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • BSM signal events at 7000 GeV.

Search for R-parity violating SUSY using events with 4 or more leptons in association with missing transverse energy in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample has a total integrated luminosity of 4.7 fb$^{-1}$.

Source code: ATLAS_2012_I1190891.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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Tools/RivetMT2.hh"

namespace Rivet {


  /// @author Peter Richardson
  class ATLAS_2012_I1190891 : public Analysis {
  public:

    /// Constructor
    ATLAS_2012_I1190891()
      : Analysis("ATLAS_2012_I1190891")
    {    }


    /// @name Analysis methods
    //@{

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

      // projection to find the electrons
      IdentifiedFinalState elecs(Cuts::abseta < 2.47 && Cuts::pT > 10*GeV);
      elecs.acceptIdPair(PID::ELECTRON);
      declare(elecs, "elecs");

      // projection to find the muons
      IdentifiedFinalState muons(Cuts::abseta < 2.4 && Cuts::pT > 10*GeV);
      muons.acceptIdPair(PID::MUON);
      declare(muons, "muons");

      // for pTmiss
      declare(VisibleFinalState(Cuts::abseta < 4.9),"vfs");

      VetoedFinalState vfs;
      vfs.addVetoPairId(PID::MUON);

      /// Jet finder
      declare(FastJets(vfs, FastJets::ANTIKT, 0.4), "AntiKtJets04");

      // all tracks (to do deltaR with leptons)
      declare(ChargedFinalState(-3.0,3.0),"cfs");

      // Book histograms
      _hist_etmiss = bookHisto1D("hist_etmiss",10,0.,500.);
      _hist_meff   = bookHisto1D("hist_m_eff",7,0.,1050.);
      _count_SR1 = bookHisto1D("count_SR1", 1, 0., 1.);
      _count_SR2 = bookHisto1D("count_SR2", 1, 0., 1.);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const double weight = event.weight();
      // get the jet candidates
      Jets cand_jets;
      foreach (const Jet& jet,
               apply<FastJets>(event, "AntiKtJets04").jetsByPt(20.0*GeV) ) {
        if ( fabs( jet.eta() ) < 2.5 ) {
          cand_jets.push_back(jet);
        }
      }

      // candidate muons
      Particles cand_mu;
      Particles chg_tracks =
        apply<ChargedFinalState>(event, "cfs").particles();
      foreach ( const Particle & mu,
                apply<IdentifiedFinalState>(event, "muons").particlesByPt() ) {
        double pTinCone = -mu.pT();
        foreach ( const Particle & track, chg_tracks ) {
          if ( deltaR(mu.momentum(),track.momentum()) <= 0.2 )
            pTinCone += track.pT();
        }
        if ( pTinCone < 1.8*GeV )
          cand_mu.push_back(mu);
      }

      // candidate electrons
      Particles cand_e;
      foreach ( const Particle & e,
                apply<IdentifiedFinalState>(event, "elecs").particlesByPt() ) {
        double pTinCone = -e.perp();
        foreach ( const Particle & track, chg_tracks ) {
          if ( deltaR(e.momentum(),track.momentum()) <= 0.2 )
            pTinCone += track.pT();
        }
        if (pTinCone/e.perp()<0.1) {
          cand_e.push_back(e);
        }
      }

      // resolve jet/lepton ambiguity
      Jets recon_jets;
      foreach ( const Jet& jet, cand_jets ) {
        bool away_from_e = true;
        foreach ( const Particle & e, cand_e ) {
          if ( deltaR(e.momentum(),jet.momentum()) <= 0.2 ) {
            away_from_e = false;
            break;
          }
        }
        if ( away_from_e )
          recon_jets.push_back( jet );
      }

      // only keep electrons more than R=0.4 from jets
      Particles cand2_e;
      for(unsigned int ie=0;ie<cand_e.size();++ie) {
        const Particle & e = cand_e[ie];
        // at least 0.4 from any jets
        bool away = true;
        foreach ( const Jet& jet, recon_jets ) {
          if ( deltaR(e.momentum(),jet.momentum()) < 0.4 ) {
            away = false;
            break;
          }
        }
        // and 0.1 from any muons
        if ( away ) {
          foreach ( const Particle & mu, cand_mu ) {
            if ( deltaR(mu.momentum(),e.momentum()) < 0.1 ) {
              away = false;
              break;
            }
          }
        }
        // and 0.1 from electrons ( keep higher energy)
        for(unsigned int ie2=0;ie2<cand_e.size();++ie2) {
          if(ie==ie2) continue;
          if ( deltaR(e.momentum(),cand_e[ie2].momentum()) < 0.1 &&
               e.E() < cand_e[ie2].E() ) {
            away = false;
            break;
          }
        }
        // if isolated keep it
        if ( away )
          cand2_e.push_back( e );
      }

      // remove e+e- pairs with mass < 20.
      Particles recon_e;
      for(unsigned int ie=0;ie<cand2_e.size();++ie) {
        bool pass = true;
        for(unsigned int ie2=0;ie2<cand2_e.size();++ie2) {
          if(cand2_e[ie].pid()*cand2_e[ie2].pid()>0) continue;
          double mtest = (cand2_e[ie].momentum()+cand2_e[ie2].momentum()).mass();
          if(mtest<=20.) {
            pass = false;
            break;
          }
        }
        if(pass) recon_e.push_back(cand2_e[ie]);
      }

      // only keep muons more than R=0.4 from jets
      Particles cand2_mu;
      for(unsigned int imu=0;imu<cand_mu.size();++imu) {
        const Particle & mu = cand_mu[imu];
        bool away = true;
        // at least 0.4 from any jets
        foreach ( const Jet& jet, recon_jets ) {
          if ( deltaR(mu.momentum(),jet.momentum()) < 0.4 ) {
            away = false;
            break;
          }
        }
        // and 0.1 from any electrona
        if ( away ) {
          foreach ( const Particle & e, cand_e ) {
            if ( deltaR(mu.momentum(),e.momentum()) < 0.1 ) {
              away = false;
              break;
            }
          }
        }
        if ( away )
          cand2_mu.push_back( mu );
      }

      // remove mu+mu- pairs with mass < 20.
      Particles recon_mu;
      for(unsigned int imu=0;imu<cand2_mu.size();++imu) {
        bool pass = true;
        for(unsigned int imu2=0;imu2<cand2_mu.size();++imu2) {
          if(cand2_mu[imu].pid()*cand2_mu[imu2].pid()>0) continue;
          double mtest = (cand2_mu[imu].momentum()+cand2_mu[imu2].momentum()).mass();
          if(mtest<=20.) {
            pass = false;
            break;
          }
        }
        if(pass) recon_mu.push_back(cand2_mu[imu]);
      }

      // pTmiss
      Particles vfs_particles =
        apply<VisibleFinalState>(event, "vfs").particles();
      FourMomentum pTmiss;
      foreach ( const Particle & p, vfs_particles ) {
        pTmiss -= p.momentum();
      }
      double eTmiss = pTmiss.pT();

      // now only use recon_jets, recon_mu, recon_e

      // reject events with less than 4 electrons and muons
      if ( recon_mu.size() + recon_e.size() < 4 ) {
        MSG_DEBUG("To few charged leptons left after selection");
        vetoEvent;
      }

      // check if passes single lepton trigger
      bool passSingle =
        ( !recon_e .empty() && recon_e[0] .perp()>25. )||
        ( !recon_mu.empty() && recon_mu[0].perp()>20.);

      // or two lepton trigger
      bool passDouble =
        ( recon_mu.size()>=2 && recon_mu[1].perp()>12.) ||
        ( recon_e .size()>=2 && recon_e [1].perp()>17.) ||
        ( !recon_e.empty() && !recon_mu.empty() &&
          recon_e[0].perp()>15. &&  recon_mu[0].perp()>10.);

      // must pass a trigger
      if( !passSingle && !passDouble ) {
        MSG_DEBUG("Hardest lepton fails trigger");
        vetoEvent;
      }

      // calculate meff
      double meff = eTmiss;
      foreach ( const Particle & e , recon_e  )
        meff += e.perp();
      foreach ( const Particle & mu, recon_mu )
        meff += mu.perp();
      foreach ( const Jet & jet, recon_jets ) {
        double pT = jet.perp();
        if(pT>40.) meff += pT;
      }

      // mass of SFOS pairs closest to the Z mass
      for(unsigned int ix=0;ix<recon_e.size();++ix) {
        for(unsigned int iy=ix+1;iy<recon_e.size();++iy) {
          if(recon_e[ix].pid()*recon_e[iy].pid()>0) continue;
          double mtest = (recon_e[ix].momentum()+recon_e[iy].momentum()).mass();
          if(mtest>81.2 && mtest<101.2) vetoEvent;
        }
      }
      for(unsigned int ix=0;ix<recon_mu.size();++ix) {
        for(unsigned int iy=ix+1;iy<recon_mu.size();++iy) {
          if(recon_mu[ix].pid()*recon_mu[iy].pid()>0) continue;
          double mtest = (recon_mu[ix].momentum()+recon_mu[iy].momentum()).mass();
          if(mtest>81.2 && mtest<101.2) vetoEvent;
        }
      }

      // make the control plots
      _hist_etmiss ->fill(eTmiss,weight);
      _hist_meff   ->fill(meff  ,weight);
      // finally the counts
      if(eTmiss>50.) _count_SR1->fill(0.5,weight);
      if(meff >300.) _count_SR2->fill(0.5,weight);
    }

    //@}

    void finalize() {
      double norm = crossSection()/femtobarn*4.7/sumOfWeights();
      scale(_hist_etmiss,norm* 50.);
      scale(_hist_meff  ,norm*150.);
      scale(_count_SR1,norm);
      scale(_count_SR2,norm);
    }

  private:

    /// @name Histograms
    //@{
    Histo1DPtr _hist_etmiss;
    Histo1DPtr _hist_meff;
    Histo1DPtr _count_SR1;
    Histo1DPtr _count_SR2;
    //@}

  };

  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(ATLAS_2012_I1190891);

}