Rivet analyses

Mass distributions in B → pp̄K(*)

Experiment: BABAR (PEP-II)

Inspire ID: 755548

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 76 (2007) 092004

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of mass distributions in B0 → pp̄KS0, B0 → pp̄K*0, B+ → pp̄K+ and B+ → pp̄K*+. The corrected data were read from the plots in the paper.

Source code:BABAR_2007_I755548.cc

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

namespace Rivet {


  /// @brief  B -> p pbar meson
  class BABAR_2007_I755548 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I755548);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(310);
      BB.addStable(313);
      BB.addStable(323);
      BB.addStable(-313);
      BB.addStable(-323);
      BB.addStable(441);
      BB.addStable(443);
      BB.addStable(100443);
      BB.addStable(10441);
      BB.addStable(20443);
      BB.addStable(445);
      declare(BB, "BB");
      // histograms
      for (unsigned int ix = 0; ix < 4; ++ix) {
        book(_h_mass[ix], 1, 1, 1 + ix);
        book(_c[ix], "TMP/c_" + toString(ix + 1));
        for (unsigned int iy = 0; iy < 2; ++iy)
          if (!(ix == 0 && iy == 1)) book(_h_mass2[iy][ix], 2, 1 + iy, 1 + ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{2212, 1}, {-2212, 1}, {310, 1}};
      static const map<PdgId, unsigned int>& mode1CC = {{2212, 1}, {-2212, 1}, {310, 1}};
      static const map<PdgId, unsigned int>& mode2 = {{2212, 1}, {-2212, 1}, {321, 1}};
      static const map<PdgId, unsigned int>& mode2CC = {{2212, 1}, {-2212, 1}, {-321, 1}};
      static const map<PdgId, unsigned int>& mode3 = {{2212, 1}, {-2212, 1}, {313, 1}};
      static const map<PdgId, unsigned int>& mode3CC = {{2212, 1}, {-2212, 1}, {-313, 1}};
      static const map<PdgId, unsigned int>& mode4 = {{2212, 1}, {-2212, 1}, {323, 1}};
      static const map<PdgId, unsigned int>& mode4CC = {{2212, 1}, {-2212, 1}, {-323, 1}};
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        int sign = BB.decaying()[ix].pid() / BB.decaying()[ix].abspid();
        int imode = -1, iK;
        if ((sign > 0 && BB.modeMatches(ix, 3, mode1)) || (sign < 0 && BB.modeMatches(ix, 3, mode1CC))) {
          imode = 0;
          iK = 310;
        }
        else if ((sign > 0 && BB.modeMatches(ix, 3, mode2)) || (sign < 0 && BB.modeMatches(ix, 3, mode2CC))) {
          imode = 1;
          iK = sign * 321;
        }
        else if ((sign > 0 && BB.modeMatches(ix, 3, mode3)) || (sign < 0 && BB.modeMatches(ix, 3, mode3CC))) {
          imode = 2;
          iK = sign * 313;
        }
        else if ((sign > 0 && BB.modeMatches(ix, 3, mode4)) || (sign < 0 && BB.modeMatches(ix, 3, mode4CC))) {
          imode = 3;
          iK = sign * 323;
        }
        else
          continue;
        _c[imode]->fill();
        const Particle& pp = BB.decayProducts()[ix].at(sign * 2212)[0];
        const Particle& pbar = BB.decayProducts()[ix].at(-sign * 2212)[0];
        const Particle& meson = BB.decayProducts()[ix].at(iK)[0];
        FourMomentum pbaryon = pp.momentum() + pbar.momentum();
        double mass = pbaryon.mass();
        _h_mass[imode]->fill(mass);
        double mph[2] = {(pp.momentum() + meson.momentum()).mass(),
                         (pbar.momentum() + meson.momentum()).mass()};
        if (imode == 0) {
          _h_mass2[0][imode]->fill(max(mph[0], mph[1]));
        }
        else {
          if (mph[0] > mph[1])
            _h_mass2[0][imode]->fill(mph[0]);
          else
            _h_mass2[1][imode]->fill(mph[1]);
        }
      }
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 4; ++ix) {
        normalize(_h_mass[ix], 1., false);
        for (unsigned int iy = 0; iy < 2; ++iy)
          if (_h_mass2[iy][ix]) scale(_h_mass2[iy][ix], 1. / *_c[ix]);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_mass[4], _h_mass2[2][4];
    CounterPtr _c[4];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2007_I755548);

}