Rivet analyses

title: BELLE_2008_I754259

$B^+\to p\bar{p} \pi^+,K^+$

Experiment: BELLE (KEKB)

Inspire ID: 754259

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 659 (2008) 80-86

Beams: * *

Beam energies: ANY

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

Mass and angular distributions in $B^+\to p\bar{p} \pi^+,K^+$ decays. The mass dsitributions were extracted from Tables 1 and 2 in the paper, while the angular distributions were extracted from the figures. The numbers are corrected for efficiency and acceptance.

Source code:BELLE_2008_I754259.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B+ -> p pbar K+, pi+ class BELLE_2008_I754259 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2008_I754259);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
  declare(ufs, "UFS");
  DecayedParticles BP(ufs);
  declare(BP, "BP");
  // histograms
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_mass[ix], 1 + ix, 1, 1);
    book(_h_angle[ix], 3, 1, 1 + ix);
  }
  book(_h_angle2, {2. * .9382722, 2.0, 2.2, 2.4, 2.6, 2.85});
  for (unsigned int ix = 0; ix < 5; ++ix) {
    book(_h_angle2->bin(ix + 1), 4, 1, 1 + ix);
  }
  book(_c, "TMP/nB");
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  DecayedParticles BP = apply<DecayedParticles>(event, "BP");
  // loop over particles
  for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
    int imode = 0, sign = 1;
    _c->fill();
    if (BP.modeMatches(ix, 3, mode1)) {
      imode = 0;
      sign = 1;
    }
    else if (BP.modeMatches(ix, 3, mode1CC)) {
      imode = 0;
      sign = -1;
    }
    else if (BP.modeMatches(ix, 3, mode2)) {
      imode = 1;
      sign = 1;
    }
    else if (BP.modeMatches(ix, 3, mode2CC)) {
      imode = 1;
      sign = -1;
    }
    else {
      continue;
    }
    const Particle& pp = BP.decayProducts()[ix].at(sign * 2212)[0];
    const Particle& pbar = BP.decayProducts()[ix].at(-sign * 2212)[0];
    const Particle& meson = BP.decayProducts()[ix].at(sign * (imode == 0 ? 321 : 211))[0];
    FourMomentum pbaryon = pp.mom() + pbar.mom();
    double mass = pbaryon.mass();
    _h_mass[imode]->fill(mass);
    if (mass > 2.85) continue;
    // boost to B rest frame
    LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
        BP.decaying()[ix].mom().betaVec());
    FourMomentum pp1 = boost.transform(pbar.mom());
    pbaryon = boost.transform(pbaryon);
    Vector3 axis = boost.transform(meson.mom()).p3().unit();
    LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(pbaryon.betaVec());
    double cosp = axis.dot(boost1.transform(pp1).p3().unit());
    _h_angle[imode]->fill(cosp);
    if (imode == 0) _h_angle2->fill(mass, cosp);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h_mass, 1e6 / *_c);
  scale(_h_angle, 1e6 / *_c);
  normalize(_h_angle2);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_mass[2], _h_angle[2];
Histo1DGroupPtr _h_angle2;
CounterPtr _c;
const map<PdgId, unsigned int> mode1 = {{2212, 1}, {-2212, 1}, {321, 1}};
const map<PdgId, unsigned int> mode1CC = {{2212, 1}, {-2212, 1}, {-321, 1}};
const map<PdgId, unsigned int> mode2 = {{2212, 1}, {-2212, 1}, {211, 1}};
const map<PdgId, unsigned int> mode2CC = {{2212, 1}, {-2212, 1}, {-211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2008_I754259);

} ```