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Rivet analyses reference

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
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
#include "Rivet/Projections/MissingMomentum.hh"
#include "Rivet/Projections/SmearedParticles.hh"
#include "Rivet/Projections/SmearedJets.hh"
#include "Rivet/Projections/SmearedMET.hh"
#include "Rivet/Tools/Cutflow.hh"
#include <tuple>

namespace Rivet {


  /// CMS search for SUSY with multijet + MET signatures in 36/fb of 13 TeV pp data
  class CMS_2017_I1594909 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(CMS_2017_I1594909);


    /// @name Analysis methods
    //@{

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

      VisibleFinalState pfall;
      declare(pfall, "PFAll");
      ChargedFinalState pfchg(Cuts::abseta < 2.5);
      declare(pfchg, "PFChg");

      FastJets jets(FinalState(Cuts::abseta < 4.9), FastJets::ANTIKT, 0.4);
      SmearedJets recojets(jets, JET_SMEAR_CMS_RUN2, [](const Jet& j){ return j.bTagged() ? 0.55 : j.cTagged() ? 0.12 : 0.016; });
      declare(recojets, "Jets");

      FinalState electrons(Cuts::abspid == PID::ELECTRON && Cuts::abseta < 2.5);
      SmearedParticles recoelectrons(electrons, ELECTRON_EFF_CMS_RUN2);
      declare(recoelectrons, "Electrons");

      FinalState muons(Cuts::abspid == PID::MUON && Cuts::abseta < 2.4);
      SmearedParticles recomuons(muons, MUON_EFF_CMS_RUN2);
      declare(recomuons, "Muons");

      VisibleFinalState calofs(Cuts::abseta < 4.9 && Cuts::abspid != PID::MUON);
      MissingMomentum met(calofs);
      SmearedMET recomet(met, MET_SMEAR_CMS_RUN2);
      declare(recomet, "MET");


      // Book counters, into a map of 3 indices since the global index is not obvious to calculate
      size_t i = 0;
      for (int j = 1; j <= 5; ++j) {
        for (int b = 1; b <= 4; ++b) {
          if (j == 1 && b == 4) continue;
          for (int k = 1; k <= 10; ++k) {
            if (j > 3 && (k == 1 || k == 4)) continue;
            stringstream s; s << "count_" << (i+1); // << "_" << j << b << k;
            _counts[make_tuple(j,b,k)] = bookCounter(s.str());
            i += 1;
          }
        }
      }
      MSG_DEBUG("Booked " << i << " signal regions (should be 174)");
      // Aggregate SR counters
      for (size_t i = 0; i < 12; ++i)
        _counts_agg[i] = bookCounter("count_agg_" + toString(i+1));


      // Book cut-flow
      _flow = Cutflow("Presel", {"Njet>=2", "HT>300", "HTmiss>300",
            "Nmuon=0", "Nmuisotrk=0", "Nelec=0", "Nelisotrk=0", "Nhadisotrk=0",
            "dPhi_miss,j1>0.5", "dPhi_miss,j2>0.5", "dPhi_miss,j3>0.3", "dPhi_miss,j4>0.3"
            });

    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {

      _flow.fillinit();

      // Find leptons and isolation particles
      const Particles elecs = apply<ParticleFinder>(event, "Electrons").particlesByPt();
      const Particles mus = apply<ParticleFinder>(event, "Muons").particlesByPt();
      const Particles pfall = apply<ParticleFinder>(event, "PFAll").particlesByPt();
      const Particles pfiso = filter_select(pfall, [](const Particle& p){ return p.isHadron() || p.pid() == PID::PHOTON; });

      // Find isolated leptons
      const Particles isoleps = filter_select(elecs+mus, [&](const Particle& l){
          const double dR = l.pT() < 50*GeV ? 0.2 : l.pT() < 200*GeV ? 10*GeV/l.pT() : 0.05;
          const double sumpt = sum(filter_select(pfiso, deltaRLess(l, dR)), pT, 0.0);
          return sumpt/l.pT() < (l.abspid() == PID::ELECTRON ? 0.1 : 0.2); //< different I criteria for e and mu
        });

      // Find other isolated tracks
      const Particles pfchg = apply<ParticleFinder>(event, "PFChg").particlesByPt();
      const Particles isochgs = filter_select(pfchg, [&](const Particle& t){
          if (t.abseta() > 2.4) return false;
          if (any(isoleps, deltaRLess(t, 0.01))) return false; //< don't count isolated leptons here
          const double sumpt = sum(filter_select(pfchg, deltaRLess(t, 0.3)), pT, -t.pT());
          return sumpt/t.pT() < ((t.abspid() == PID::ELECTRON || t.abspid() == PID::MUON) ? 0.2 : 0.1);
        });

      // Find and isolate jets
      const Jets jets = apply<JetAlg>(event, "Jets").jetsByPt(Cuts::pT > 30*GeV);
      const Jets isojets = filter_select(jets, Cuts::abseta < 2.4); //< @todo Isolation from leptons?!?
      const int njets = isojets.size();
      const Jets isobjets = filter_select(isojets, hasBTag());
      const int nbjets = isobjets.size();
      MSG_DEBUG("Njets = " << jets.size() << ", Nisojets = " << njets << ", Nbjets = " << nbjets);

      // Calculate HT, HTmiss, and pTmiss quantities
      const double ht = sum(jets, pT, 0.0);
      const Vector3 vhtmiss = -sum(jets, pTvec, Vector3());
      const double htmiss = vhtmiss.perp();
      const Vector3& vptmiss = -apply<SmearedMET>(event, "MET").vectorEt();
      const double ptmiss = vptmiss.perp();
      MSG_DEBUG("HT = " << ht/GeV << " GeV, HTmiss = " << htmiss/GeV << " GeV");


      /////////////////////////////////////
      // Event selection

      // Njet cut
      if (njets < 2) vetoEvent;
      _flow.fill(1);
      // HT cut
      if (ht < 300*GeV) vetoEvent;
      _flow.fill(2);
      // HTmiss cut
      if (htmiss < 300*GeV) vetoEvent;
      _flow.fill(3);

      // Isolated leptons cut
      if (!filter_select(isoleps, Cuts::pT > 10*GeV).empty()) vetoEvent;
      // Isolated tracks cut
      for (const Particle& t : isochgs) {
        const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
        if (mT < 100*GeV) continue;
        const double pTmax = (t.abspid() == PID::ELECTRON || t.abspid() == PID::MUON) ? 5*GeV : 10*GeV;
        if (t.pT() > pTmax) vetoEvent;
      }
      //
      // // Inefficiently separated version of isolation cuts for detailed cutflow debugging
      // // Muon cut
      // if (!filter_select(isoleps, Cuts::pT > 10*GeV && Cuts::abspid == PID::MUON).empty()) vetoEvent;
      // _flow.fill(4);
      // // Muon isotrk cut
      // for (const Particle& t : filter_select(isochgs, Cuts::abspid == PID::MUON)) {
      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
      //   if (mT > 100*GeV && t.pT() > 5*GeV) vetoEvent;
      // }
      // _flow.fill(5);
      // // Electron cut
      // if (!filter_select(isoleps, Cuts::pT > 10*GeV && Cuts::abspid == PID::ELECTRON).empty()) vetoEvent;
      // _flow.fill(6);
      // // Electron isotrk cut
      // for (const Particle& t : filter_select(isochgs, Cuts::abspid == PID::ELECTRON)) {
      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
      //   if (mT > 100*GeV && t.pT() > 5*GeV) vetoEvent;
      // }
      // _flow.fill(7);
      // // Hadron isotrk cut
      // for (const Particle& t : filter_select(isochgs, Cuts::abspid != PID::ELECTRON && Cuts::abspid != PID::MUON)) {
      //   const double mT = sqrt(2*t.pT()*ptmiss * (1 - cos(deltaPhi(t, vptmiss))) );
      //   if (mT > 100*GeV && t.pT() > 10*GeV) vetoEvent;
      // }
      _flow.fill(8);


      // dPhi(jet,HTmiss) cuts
      if (deltaPhi(vhtmiss, isojets[0]) < 0.5) vetoEvent;
      _flow.fill(9);
      if (deltaPhi(vhtmiss, isojets[1]) < 0.5) vetoEvent;
      _flow.fill(10);
      if (njets >= 3 && deltaPhi(vhtmiss, isojets[2]) < 0.3) vetoEvent;
      _flow.fill(11);
      if (njets >= 4 && deltaPhi(vhtmiss, isojets[3]) < 0.3) vetoEvent;
      _flow.fill(12);


      /////////////////////////////////////
      // Find SR index and fill counter

      const double w = event.weight();

      const int idx_j = binIndex(njets, vector<int>{2,3,5,7,9}, true);
      const int idx_b = binIndex(nbjets, vector<int>{0,1,2,3}, true);
      int idx_k = -1;
      if (inRange(htmiss/GeV, 300, 350)) {
        idx_k = ht < 500*GeV ? 1 : ht < 1000*GeV ? 2 : 3;
      } else if (inRange(htmiss/GeV, 350, 500) && ht > 350*GeV) {
        idx_k = ht < 500*GeV ? 4 : ht < 1000*GeV ? 5 : 6;
      } else if (inRange(htmiss/GeV, 500, 750) && ht > 500*GeV) {
        idx_k = ht < 1000*GeV ? 7 : 8;
      } else if (htmiss/GeV > 750 && ht > 750*GeV) {
        idx_k = ht < 1500*GeV ? 9 : 10;
      }

      // Fill via 3-tuple index
      if (idx_j >= 0 && idx_b >= 0 && idx_k >= 0) {
        const auto idx = make_tuple(idx_j+1,idx_b+1,idx_k);
        if (has_key(_counts, idx)) _counts[idx]->fill(w);
      }


      /////////////////////////////////////
      // Aggregate SRs

      // Region Njet Nb-jet HT [GeV] HTmiss [GeV] Parton multiplicity Heavy flavor ? m
      if (njets >= 2 && nbjets == 0 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[0]->fill(w);
      if (njets >= 3 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[1]->fill(w);
      if (njets >= 5 && nbjets == 0 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[2]->fill(w);
      if (njets >= 5 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[3]->fill(w);
      if (njets >= 9 && nbjets == 0 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[4]->fill(w);
      if (njets >= 2 && nbjets >= 2 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[5]->fill(w);
      if (njets >= 3 && nbjets >= 1 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[6]->fill(w);
      if (njets >= 5 && nbjets >= 3 && ht >=  500*GeV && htmiss >= 500*GeV) _counts_agg[7]->fill(w);
      if (njets >= 5 && nbjets >= 2 && ht >= 1500*GeV && htmiss >= 750*GeV) _counts_agg[8]->fill(w);
      if (njets >= 9 && nbjets >= 3 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[9]->fill(w);
      if (njets >= 7 && nbjets >= 1 && ht >=  300*GeV && htmiss >= 300*GeV) _counts_agg[10]->fill(w);
      if (njets >= 5 && nbjets >= 1 && ht >=  750*GeV && htmiss >= 750*GeV) _counts_agg[11]->fill(w);

    }


    /// Normalise histograms etc., after the run
    void finalize() {

      const double norm = 35.9*crossSection()/femtobarn;
      const double sf = norm/sumOfWeights();

      for (auto& idx_cptr : _counts)
        scale(idx_cptr.second, sf);
      for (CounterPtr& cptr : _counts_agg)
        scale(cptr, sf);

      _flow.scale(sf);
      MSG_INFO("CUTFLOWS:\n\n" << _flow);

    }

    //@}


  private:

    Cutflow _flow;

    map<tuple<int,int,int>, CounterPtr> _counts;
    CounterPtr _counts_agg[12];

  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CMS_2017_I1594909);


}