Rivet analyses

title: BELLE_2008_I778726

$B^0\to p\bar{p}K^{0}$ and $B^+\to p\bar{p}K^{+}$

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 $B^0\to p\bar{p}K^{0}$ and $B^+\to p\bar{p}K^{+}$ decays. The branchingf ratio vs $p\bar{p}$ 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++ // -- 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);

} ```