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CMS_2017_I1594909

Search for SUSY in multijet events with missing transverse momentum in $pp$ collisions at 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1594909
Status: VALIDATED
Authors:
  • Andy Buckley
References: Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
  • BSM signal events.

A search for supersymmetry based on multijet events with large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 13\,\text{TeV}$. The data, corresponding to an integrated luminosity of 35.9/fb, were collected with the CMS detector at the CERN LHC in 2016. The analysis utilizes four-dimensional exclusive search regions defined in terms of the number of jets, the number of tagged bottom-quark jets, the scalar sum of jet transverse momenta, and the magnitude of the vector sum of jet transverse momenta. This coding presents the fully detailed 174 signal regions, as well as 12 aggregate signal regions.

Source code: CMS_2017_I1594909.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/FastJets.hh"
  5#include "Rivet/Projections/ChargedFinalState.hh"
  6#include "Rivet/Projections/VisibleFinalState.hh"
  7#include "Rivet/Projections/MissingMomentum.hh"
  8#include "Rivet/Projections/SmearedParticles.hh"
  9#include "Rivet/Projections/SmearedJets.hh"
 10#include "Rivet/Projections/SmearedMET.hh"
 11#include "Rivet/Tools/Cutflow.hh"
 12#include <tuple>
 13
 14namespace Rivet {
 15
 16
 17  /// CMS search for SUSY with multijet + MET signatures in 36/fb of 13 TeV pp data
 18  class CMS_2017_I1594909 : public Analysis {
 19  public:
 20
 21    /// Constructor
 22    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2017_I1594909);
 23
 24
 25    /// @name Analysis methods
 26    //@{
 27
 28    /// Book histograms and initialise projections before the run
 29    void init() {
 30
 31      VisibleFinalState pfall;
 32      declare(pfall, "PFAll");
 33      ChargedFinalState pfchg(Cuts::abseta < 2.5);
 34      declare(pfchg, "PFChg");
 35
 36      FastJets jets(FinalState(Cuts::abseta < 4.9), FastJets::ANTIKT, 0.4);
 37      SmearedJets recojets(jets, JET_SMEAR_CMS_RUN2, [](const Jet& j){ return j.bTagged() ? 0.55 : j.cTagged() ? 0.12 : 0.016; });
 38      declare(recojets, "Jets");
 39
 40      FinalState electrons(Cuts::abspid == PID::ELECTRON && Cuts::abseta < 2.5);
 41      SmearedParticles recoelectrons(electrons, ELECTRON_EFF_CMS_RUN2);
 42      declare(recoelectrons, "Electrons");
 43
 44      FinalState muons(Cuts::abspid == PID::MUON && Cuts::abseta < 2.4);
 45      SmearedParticles recomuons(muons, MUON_EFF_CMS_RUN2);
 46      declare(recomuons, "Muons");
 47
 48      VisibleFinalState calofs(Cuts::abseta < 4.9 && Cuts::abspid != PID::MUON);
 49      MissingMomentum met(calofs);
 50      SmearedMET recomet(met, MET_SMEAR_CMS_RUN2);
 51      declare(recomet, "MET");
 52
 53
 54      // Book counters, into a map of 3 indices since the global index is not obvious to calculate
 55      size_t i = 0;
 56      for (int j = 1; j <= 5; ++j) {
 57        for (int b = 1; b <= 4; ++b) {
 58          if (j == 1 && b == 4) continue;
 59          for (int k = 1; k <= 10; ++k) {
 60            if (j > 3 && (k == 1 || k == 4)) continue;
 61            stringstream s; s << "count_" << (i+1); // << "_" << j << b << k;
 62            book(_counts[std::make_tuple(j,b,k)], s.str());
 63            i += 1;
 64          }
 65        }
 66      }
 67      MSG_DEBUG("Booked " << i << " signal regions (should be 174)");
 68      // Aggregate SR counters
 69      for (size_t i = 0; i < 12; ++i)
 70        book(_counts_agg[i], "count_agg_" + toString(i+1));
 71
 72
 73      // Book cut-flow
 74      _flow = Cutflow("Presel", {"Njet>=2", "HT>300", "HTmiss>300",
 75            "Nmuon=0", "Nmuisotrk=0", "Nelec=0", "Nelisotrk=0", "Nhadisotrk=0",
 76            "dPhi_miss,j1>0.5", "dPhi_miss,j2>0.5", "dPhi_miss,j3>0.3", "dPhi_miss,j4>0.3"
 77            });
 78
 79    }
 80
 81
 82    /// Perform the per-event analysis
 83    void analyze(const Event& event) {
 84
 85      _flow.fillinit();
 86
 87      // Find leptons and isolation particles
 88      const Particles elecs = apply<ParticleFinder>(event, "Electrons").particlesByPt();
 89      const Particles mus = apply<ParticleFinder>(event, "Muons").particlesByPt();
 90      const Particles pfall = apply<ParticleFinder>(event, "PFAll").particlesByPt();
 91      const Particles pfiso = filter_select(pfall, [](const Particle& p){ return p.isHadron() || p.pid() == PID::PHOTON; });
 92
 93      // Find isolated leptons
 94      const Particles isoleps = filter_select(elecs+mus, [&](const Particle& l){
 95          const double dR = l.pT() < 50*GeV ? 0.2 : l.pT() < 200*GeV ? 10*GeV/l.pT() : 0.05;
 96          const double sumpt = sum(filter_select(pfiso, deltaRLess(l, dR)), Kin::pT, 0.0);
 97          return sumpt/l.pT() < (l.abspid() == PID::ELECTRON ? 0.1 : 0.2); //< different I criteria for e and mu
 98        });
 99
100      // Find other isolated tracks
101      const Particles pfchg = apply<ParticleFinder>(event, "PFChg").particlesByPt();
102      const Particles isochgs = filter_select(pfchg, [&](const Particle& t){
103          if (t.abseta() > 2.4) return false;
104          if (any(isoleps, deltaRLess(t, 0.01))) return false; //< don't count isolated leptons here
105          const double sumpt = sum(filter_select(pfchg, deltaRLess(t, 0.3)), Kin::pT, -t.pT());
106          return sumpt/t.pT() < ((t.abspid() == PID::ELECTRON || t.abspid() == PID::MUON) ? 0.2 : 0.1);
107        });
108
109      // Find and isolate jets
110      const Jets jets = apply<JetAlg>(event, "Jets").jetsByPt(Cuts::pT > 30*GeV);
111      const Jets cjets = filter_select(jets, Cuts::abseta < 2.4);
112      const Jets isojets = cjets; //discardIfAnyDeltaRLess(cjets, elecs+mus, 0.4);
113      const int njets = isojets.size();
114      const Jets isobjets = filter_select(isojets, hasBTag());
115      const int nbjets = isobjets.size();
116      MSG_DEBUG("Njets = " << jets.size() << ", Nisojets = " << njets << ", Nbjets = " << nbjets);
117
118      // Calculate HT, HTmiss, and pTmiss quantities
119      const double ht = sum(jets, Kin::pT, 0.0);
120      const Vector3 vhtmiss = -sum(jets, pTvec, Vector3());
121      const double htmiss = vhtmiss.perp();
122      const Vector3& vptmiss = -apply<SmearedMET>(event, "MET").vectorEt();
123      const double ptmiss = vptmiss.perp();
124      MSG_DEBUG("HT = " << ht/GeV << " GeV, HTmiss = " << htmiss/GeV << " GeV");
125
126
127      /////////////////////////////////////
128      // Event selection
129
130      // Njet cut
131      if (njets < 2) vetoEvent;
132      _flow.fill(1);
133      // HT cut
134      if (ht < 300*GeV) vetoEvent;
135      _flow.fill(2);
136      // HTmiss cut
137      if (htmiss < 300*GeV) vetoEvent;
138      _flow.fill(3);
139
140      // Isolated leptons cut
141      if (!filter_select(isoleps, Cuts::pT > 10*GeV).empty()) vetoEvent;
142      // Isolated tracks cut
143      for (const Particle& t : isochgs) {
144        const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
145        if (mT < 100*GeV) continue;
146        const double pTmax = (t.abspid() == PID::ELECTRON || t.abspid() == PID::MUON) ? 5*GeV : 10*GeV;
147        if (t.pT() > pTmax) vetoEvent;
148      }
149      //
150      // // Inefficiently separated version of isolation cuts for detailed cutflow debugging
151      // // Muon cut
152      // if (!filter_select(isoleps, Cuts::pT > 10*GeV && Cuts::abspid == PID::MUON).empty()) vetoEvent;
153      // _flow.fill(4);
154      // // Muon isotrk cut
155      // for (const Particle& t : filter_select(isochgs, Cuts::abspid == PID::MUON)) {
156      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
157      //   if (mT > 100*GeV && t.pT() > 5*GeV) vetoEvent;
158      // }
159      // _flow.fill(5);
160      // // Electron cut
161      // if (!filter_select(isoleps, Cuts::pT > 10*GeV && Cuts::abspid == PID::ELECTRON).empty()) vetoEvent;
162      // _flow.fill(6);
163      // // Electron isotrk cut
164      // for (const Particle& t : filter_select(isochgs, Cuts::abspid == PID::ELECTRON)) {
165      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
166      //   if (mT > 100*GeV && t.pT() > 5*GeV) vetoEvent;
167      // }
168      // _flow.fill(7);
169      // // Hadron isotrk cut
170      // for (const Particle& t : filter_select(isochgs, Cuts::abspid != PID::ELECTRON && Cuts::abspid != PID::MUON)) {
171      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
172      //   if (mT > 100*GeV && t.pT() > 10*GeV) vetoEvent;
173      // }
174      _flow.fill(8);
175
176
177      // dPhi(jet,HTmiss) cuts
178      if (deltaPhi(vhtmiss, isojets[0]) < 0.5) vetoEvent;
179      _flow.fill(9);
180      if (deltaPhi(vhtmiss, isojets[1]) < 0.5) vetoEvent;
181      _flow.fill(10);
182      if (njets >= 3 && deltaPhi(vhtmiss, isojets[2]) < 0.3) vetoEvent;
183      _flow.fill(11);
184      if (njets >= 4 && deltaPhi(vhtmiss, isojets[3]) < 0.3) vetoEvent;
185      _flow.fill(12);
186
187
188      /////////////////////////////////////
189      // Find SR index and fill counter
190
191      const double w = 1.0;
192
193      const int idx_j = binIndex(njets, vector<int>{2,3,5,7,9}, true);
194      const int idx_b = binIndex(nbjets, vector<int>{0,1,2,3}, true);
195      int idx_k = -1;
196      if (inRange(htmiss/GeV, 300, 350)) {
197        idx_k = ht < 500*GeV ? 1 : ht < 1000*GeV ? 2 : 3;
198      } else if (inRange(htmiss/GeV, 350, 500) && ht > 350*GeV) {
199        idx_k = ht < 500*GeV ? 4 : ht < 1000*GeV ? 5 : 6;
200      } else if (inRange(htmiss/GeV, 500, 750) && ht > 500*GeV) {
201        idx_k = ht < 1000*GeV ? 7 : 8;
202      } else if (htmiss/GeV > 750 && ht > 750*GeV) {
203        idx_k = ht < 1500*GeV ? 9 : 10;
204      }
205
206      // Fill via 3-tuple index
207      if (idx_j >= 0 && idx_b >= 0 && idx_k >= 0) {
208        const auto idx = std::make_tuple(idx_j+1,idx_b+1,idx_k);
209        if (has_key(_counts, idx)) _counts[idx]->fill(w);
210      }
211
212
213      /////////////////////////////////////
214      // Aggregate SRs
215
216      // Region Njet Nb-jet HT [GeV] HTmiss [GeV] Parton multiplicity Heavy flavor ? ∆m
217      if (njets >= 2 && nbjets == 0 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[0]->fill(w);
218      if (njets >= 3 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[1]->fill(w);
219      if (njets >= 5 && nbjets == 0 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[2]->fill(w);
220      if (njets >= 5 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[3]->fill(w);
221      if (njets >= 9 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[4]->fill(w);
222      if (njets >= 2 && nbjets >= 2 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[5]->fill(w);
223      if (njets >= 3 && nbjets >= 1 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[6]->fill(w);
224      if (njets >= 5 && nbjets >= 3 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[7]->fill(w);
225      if (njets >= 5 && nbjets >= 2 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[8]->fill(w);
226      if (njets >= 9 && nbjets >= 3 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[9]->fill(w);
227      if (njets >= 7 && nbjets >= 1 && ht >=  300*GeV && htmiss >= 300*GeV) _counts_agg[10]->fill(w);
228      if (njets >= 5 && nbjets >= 1 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[11]->fill(w);
229
230    }
231
232
233    /// Normalise histograms etc., after the run
234    void finalize() {
235
236      const double norm = 35.9*crossSection()/femtobarn;
237      const double sf = norm/sumOfWeights();
238
239      for (auto& idx_cptr : _counts)
240        scale(idx_cptr.second, sf);
241      for (CounterPtr& cptr : _counts_agg)
242        scale(cptr, sf);
243
244      _flow.scale(sf);
245      MSG_INFO("CUTFLOWS:\n\n" << _flow);
246
247    }
248
249    //@}
250
251
252  private:
253
254    Cutflow _flow;
255
256    map<tuple<int,int,int>, CounterPtr> _counts;
257    CounterPtr _counts_agg[12];
258
259  };
260
261
262  // The hook for the plugin system
263  RIVET_DECLARE_PLUGIN(CMS_2017_I1594909);
264
265
266}