Rivet analyses

Ratio of strange to non-strange B meson production at 7,8 and 13 TeV

Experiment: LHCB (LHC)

Inspire ID: 1760257

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 124 (2020) 12, 122002

Beams: p+ p+

Beam energies: (3500.0, 3500.0); (4000.0, 4000.0); (6500.0, 6500.0)GeV

Run details: - b hadron production

Ratio of strange to non-strange B meson production at 7,8 and 13 TeV.

Source code:LHCB_2019_I1760257.cc

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

namespace Rivet {


  /// @brief strange fraction at 7,8,13 TeV
  class LHCB_2019_I1760257 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2019_I1760257);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projection
      declare(UnstableParticles(), "UFS");

      for (double eVal : allowedEnergies()) {
        const int en(eVal+0.5);
        if (isCompatibleWithSqrtS(eVal)) {
          if (en == 7000)       _sqs = 0;
          else if (en == 8000)  _sqs = 1;
          else                  _sqs = 2;
        }
      }
      raiseBeamErrorIf(_sqs < 0);
      //histograms
      for (size_t ix=0; ix<2; ++ix) {
        book(_c_B[ix], "TMP/c_B_"+toString(ix+1),  refData<YODA::BinnedEstimate<string> >(1,1,1));
        for (size_t iy=0; iy<3; ++iy) {
          book(_h_pT[ix][iy],"TMP/h_pT_"+toString(ix+1)+"_"+toString(iy+1), refData(5,1,1+iy));
          book(_h_pL[ix][iy], "TMP/h_pL_"+toString(ix+1)+"_"+toString(iy+1), refData(3,1,1+iy));
        }
        for (size_t iy=0; iy<5; ++iy) {
          book(_h_kin[ix][iy], "TMP/h_kin_"+toString(ix+1)+"_"+toString(iy+1), refData(4,1,1+iy));
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      if (_edges.empty()) _edges = _c_B[0]->xEdges();
      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==521 or Cuts::abspid==531)) {
        // kinematic region
        // rapidity cuts
        double y = p.rapidity(), eta = p.eta();
        if (y<2. || y> 4.5 || eta<2. || eta>6.5) continue;
        // momentum cuts
        double pT = p.perp()/GeV, pL = p.momentum().z()/GeV, pTot=p.momentum().p3().mod()/GeV;
        if (pT<0.5 || pT>40. || pTot<20. || pTot>700. || pL<20. || pL>700.) continue;
        // type of meson
        unsigned int imeson = (p.abspid()%100)/10 - 2;
        _c_B [imeson]->fill(_edges[_sqs]);
        if (_sqs==2) _c_B [imeson]->fill(_edges[3]);
        _h_pT[imeson][_sqs]->fill(pT);
        if (pL<75.)       _h_pL[imeson][0]->fill(pT);
        else if (pL<125.) _h_pL[imeson][1]->fill(pT);
        else if (pL<700.) _h_pL[imeson][2]->fill(pT);
        _h_kin[imeson][0]->fill(pTot);
        _h_kin[imeson][1]->fill(pL  );
        _h_kin[imeson][2]->fill(pT  );
        _h_kin[imeson][3]->fill(eta );
        _h_kin[imeson][4]->fill(y   );
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // ratio of branching ratios from PDSG 2020
      const double brRatio = 1.08e-3/1.02e-3;
      for (size_t iy=0; iy<5; ++iy) {
        Estimate1DPtr tmp;
        book(tmp, 4, 1, iy+1);
        divide(_h_kin[1][iy], _h_kin[0][iy], tmp);
        tmp->scale(brRatio);
        if (iy>=3) continue;
        book(tmp, 3, 1, iy+1);
        divide(_h_pL[1][iy], _h_pL[0][iy], tmp);
        tmp->scale(brRatio);
        book(tmp, 5, 1, 1+iy);
        divide(_h_pT[1][iy], _h_pT[0][iy], tmp);
        tmp->scale(brRatio);
      }
      // ratio
      BinnedEstimatePtr<string> ratio;
      book(ratio, 1, 1, 1);
      divide(_c_B[1], _c_B[0], ratio);
      ratio->scale(brRatio);
    }

    /// @}


    /// @name Histograms
    /// @{
    int _sqs = -1;
    vector<string> _edges;
    BinnedHistoPtr<string> _c_B[2];
    Histo1DPtr _h_pL[2][3],_h_kin[2][5], _h_pT[2][3];
    /// @}

  };


  RIVET_DECLARE_PLUGIN(LHCB_2019_I1760257);

}