Rivet analyses

Inclusive b-jet production in pp collisions at 7 TeV

Experiment: CMS (LHC)

Inspire ID: 1089835

Status: VALIDATED

Authors: - cms-pag-conveners-bph@cern.ch - Paolo Gunnellini

References: - Expt page: CMS-BPH-11-022 - JHEP 1204 (2012) 084 - DOI:10.1007/JHEP04(2012)084 - arXiv: 1202.4617

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - QCD events with transverse momentum greater than 10 GeV

The inclusive b-jet production cross section in pp collisions at a center-of-mass energy of 7 TeV is measured using data collected by the CMS experiment at the LHC. The cross section is presented as a function of the jet transverse momentum in the range 18 < pT < 200 GeV for several rapidity intervals. The results are also given as the ratio of the b-jet production cross section to the inclusive jet production cross section. The measurement is performed with two different analyses, which differ in their trigger selection and b-jet identification: a jet analysis that selects events with a b jet using a sample corresponding to an integrated luminosity of 34 inverse picobarns, and a muon analysis requiring a b jet with a muon based on an integrated luminosity of 3 inverse picobarns. In both approaches the b jets are identified by requiring a secondary vertex. The results from the two methods are in agreement with each other and with next-to-leading order calculations, as well as with predictions based on the PYTHIA event generator.

Source code:CMS_2012_I1089835.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/Logging.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {


  /// @brief Inclusive b-jet production in pp collisions at 7 TeV
  class CMS_2012_I1089835 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2012_I1089835);


    /// @name Analysis methods
    /// @{

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

      const FinalState cnfs;
      declare(cnfs, "FS");
      declare(FastJets(cnfs, JetAlg::ANTIKT, 0.5), "Jets");

      book(_h_dsigdpty05, 4, 1, 1);
      book(_h_dsigdpty10, 5, 1, 1);
      book(_h_dsigdpty15, 6, 1, 1);
      book(_h_dsigdpty20, 7, 1, 1);
      book(_h_dsigdpty22, 8, 1, 1);

    }


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

      const FastJets& fastjets = apply<FastJets>(event, "Jets");
      const Jets jets = fastjets.jetsByPt(Cuts::pT > 10*GeV);

      for (const Jet& j : jets) {

        const double ptB= j.pT();
        const double yB= j.rapidity();

        if (j.bTagged()) {

          if( fabs(yB) < 0.5) { _h_dsigdpty05->fill( ptB, 1.0 );}
          else if( fabs(yB) >= 0.5 && fabs(yB) < 1.0) { _h_dsigdpty10->fill( ptB, 1.0 );}
          else if( fabs(yB) >= 1.0 && fabs(yB) < 1.5) { _h_dsigdpty15->fill( ptB, 1.0 );}
          else if( fabs(yB) >= 1.5 && fabs(yB) < 2.0) { _h_dsigdpty20->fill( ptB, 1.0 );}
          else if( fabs(yB) >= 2.0 && fabs(yB) < 2.2) { _h_dsigdpty22->fill( ptB, 1.0 );}
        }
      }
    }

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

      double invlumi = crossSection()/picobarn/sumOfWeights();

      scale(_h_dsigdpty05, invlumi);
      scale(_h_dsigdpty10, invlumi);
      scale(_h_dsigdpty15, invlumi);
      scale(_h_dsigdpty20, invlumi);
      scale(_h_dsigdpty22, invlumi/0.4);

    }

    /// @}


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _h_dsigdpty05;
    Histo1DPtr _h_dsigdpty10;
    Histo1DPtr _h_dsigdpty15;
    Histo1DPtr _h_dsigdpty20;
    Histo1DPtr _h_dsigdpty22;
    /// @}

  };


  RIVET_DECLARE_PLUGIN(CMS_2012_I1089835);

}