Rivet analyses

B0 → pp̄K*0 and B+ → pp̄K*+

Experiment: BELLE (KEKB)

Inspire ID: 778726

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 100 (2008) 251801

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 and B+ mesons, originally Upsilon(4S) decays

Kinematic distributions in B0 → pp̄K*0 and B+ → pp̄K*+ decays. The branchingf ratio vs pp̄ was taken from Table I in the paper, while the uncorrected kaon helicity angle and corrected proton angle were read from figures in the paper.

Source code:BELLE_2008_I778726.cc

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

namespace Rivet {


  /// @brief B -> p pbar K*
  class BELLE_2008_I778726 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2008_I778726);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(313);
      BB.addStable(-313);
      BB.addStable(323);
      BB.addStable(-323);
      declare(BB, "BB");
      // histos
      for (unsigned int iy = 0; iy < 2; ++iy) {
        book(_c[iy], "TMP/c_+" + toString(iy + 1));
        for (unsigned int ix = 0; ix < 3; ++ix) {
          book(_h[ix][iy], ix + 1, 1, 1 + iy);
        }
      }
    }

    bool isK(int id) const {
      return id == 321 || id == 311 || id == 310 || id == 130;
    }

    bool isPi(int id) const {
      return id == 211 || id == 111;
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        int sign = 1;
        int imode = 0;
        if (BB.decaying()[ix].abspid() == 511) {
          _c[0]->fill();
          if (BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode1)) {
            sign = 1;
          }
          else if (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode1CC)) {
            sign = -1;
          }
          else {
            continue;
          }
        }
        else {
          imode = 1;
          _c[1]->fill();
          if (BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode2)) {
            sign = 1;
          }
          else if (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode2CC)) {
            sign = -1;
          }
          else {
            continue;
          }
        }
        int iK = imode == 0 ? 313 : 323;
        const Particle& pp = BB.decayProducts()[ix].at(sign * 2212)[0];
        const Particle& pbar = BB.decayProducts()[ix].at(-sign * 2212)[0];
        const Particle& Kstar = BB.decayProducts()[ix].at(sign * iK)[0];
        FourMomentum ppbar = pp.mom() + pbar.mom();
        double mppbar = ppbar.mass();
        _h[0][imode]->fill(mppbar);
        if (mppbar < 2.85) {
          // boost to B rest frame
          LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
              BB.decaying()[ix].mom().betaVec());
          FourMomentum pKstar = boost.transform(Kstar.mom());
          // proton helicity angle
          FourMomentum pProton = boost.transform(pp.mom());
          ppbar = boost.transform(ppbar);
          LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(ppbar.betaVec());
          pProton = boost1.transform(pProton);
          _h[2][imode]->fill(pKstar.p3().unit().dot(pProton.p3().unit()));
          Particle KK;
          if (isK(Kstar.children()[0].abspid()) && isPi(Kstar.children()[1].abspid())) {
            KK = Kstar.children()[0];
          }
          else if (isK(Kstar.children()[1].abspid()) && isPi(Kstar.children()[0].abspid())) {
            KK = Kstar.children()[1];
          }
          else {
            continue;
          }
          FourMomentum pK = boost.transform(KK.mom());
          const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
          pK = boost3.transform(pK);
          FourMomentum pB = boost3.transform(boost.transform(BB.decaying()[ix].mom()));
          const double cosK = -pB.p3().unit().dot(pK.p3().unit());
          _h[1][imode]->fill(cosK);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 3; ++ix) {
        for (unsigned int iy = 0; iy < 2; ++iy) {
          if (ix == 0)
            scale(_h[ix][iy], 1e6 / *_c[iy]);
          else
            normalize(_h[ix][iy], 1.0, false);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3][2];
    CounterPtr _c[2];
    const map<PdgId, unsigned int> mode1 = {{2212, 1}, {-2212, 1}, {313, 1}};
    const map<PdgId, unsigned int> mode1CC = {{2212, 1}, {-2212, 1}, {-313, 1}};
    const map<PdgId, unsigned int> mode2 = {{2212, 1}, {-2212, 1}, {323, 1}};
    const map<PdgId, unsigned int> mode2CC = {{2212, 1}, {-2212, 1}, {-323, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2008_I778726);

}