Rivet analyses

Relative production rates of χb1(1P) to χb2(1P) at 7 TeV

Experiment: LHCB (LHC)

Inspire ID: 1315113

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 10 (2014) 088

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - chi_b(1,2) production

Measurement of the relative rates of prompt χb1 to χb2 production at 7 TeV using the decay to Υγ by the LHCb collaboration.

Source code:LHCB_2014_I1315113.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief chi_b production at 7 TeV
  class LHCB_2014_I1315113 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2014_I1315113);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(UnstableParticles(), "UFS");
      for (unsigned int ichi = 0; ichi < 2; ++ichi) {
        book(_h_chi[ichi], "TMP/h_CHI_" + toString(ichi), refData(1, 1, 1));
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

      for (const Particle& p : ufs.particles(Cuts::pid == 20553 || Cuts::pid == 555)) {
        // Upsilon /gamma mode
        if (p.children().size() != 2) continue;
        Particle ups;
        if (p.children()[0].pid() == 22 && p.children()[1].pid() == 553) {
          ups = p.children()[1];
        }
        else if (p.children()[1].pid() == 22 && p.children()[0].pid() == 553) {
          ups = p.children()[0];
        }
        else
          continue;
        double absrap = ups.absrap();
        if (absrap < 2. || absrap > 4.5) continue;
        unsigned int ichi = p.pid() == 20553 ? 0 : 1;
        _h_chi[ichi]->fill(ups.perp());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      vector<double> br = {.352, 0.18};
      for (unsigned int ix = 0; ix < 2; ++ix) scale(_h_chi[ix], 1. / br[ix]);
      Estimate1DPtr tmp;
      book(tmp, 1, 1, 1);
      divide(_h_chi[0], _h_chi[1], tmp);
      tmp->scale(br[1] / br[0]);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_chi[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(LHCB_2014_I1315113);

}