Rivet analyses

title: BELLE_2023_I2099998

Mass and helicity angles in $B^+\to K^+K^-\pi^+$

Experiment: BELLE (KEKB)

Inspire ID: 2099998

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 107 (2023) 3, 032013

Beams: * *

Beam energies: ANY

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

Mass and helicity angles in $B^+\to K^+K^-\pi^+$. The data for the mass distributions was taken from tables I and IV in the paper, and the corrected data for the helicity angles from figure 4.

Source code:BELLE_2023_I2099998.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B+ -> K+ K- pi+ class BELLE_2023_I2099998 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2023_I2099998);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
  declare(ufs, "UFS");
  DecayedParticles BP(ufs);
  BP.addStable(PID::K0S);
  BP.addStable(411);
  BP.addStable(-411);
  BP.addStable(421);
  BP.addStable(-421);
  BP.addStable(10441);
  declare(BP, "BP");
  // histograms
  for (unsigned int ix = 0; ix < 3; ++ix) {
    book(_h[ix], 1 + ix, 1, 1);
  }
  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 sign = BP.decaying()[ix].pid() > 0 ? 1 : -1;
    _c->fill();
    if ((sign > 0 and BP.modeMatches(ix, 3, mode)) || (sign < 0 and BP.modeMatches(ix, 3, modeCC))) {
      //      // momenta
      FourMomentum Kp = BP.decayProducts()[ix].at(321 * sign)[0].mom();
      FourMomentum Km = BP.decayProducts()[ix].at(-321 * sign)[0].mom();
      FourMomentum pip = BP.decayProducts()[ix].at(211 * sign)[0].mom();
      // masses
      double mKpi = (Km + pip).mass();
      double mKK = (Kp + Km).mass();
      _h[0]->fill(mKK);
      _h[1]->fill(mKpi);
      if (mKK > 1.1) continue;
      LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
          BP.decaying()[ix].mom().betaVec());
      FourMomentum pKK = boost.transform(Kp + Km);
      LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pKK.betaVec());
      double cTheta = boost2.transform(boost.transform(Kp)).p3().unit().dot(pKK.p3().unit());
      _h[2]->fill(cTheta);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h, 1e7 / *_c);
  normalize(_h[2], 1.0, false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
CounterPtr _c;
const map<PdgId, unsigned int> mode = {{321, 1}, {-321, 1}, {211, 1}};
const map<PdgId, unsigned int> modeCC = {{321, 1}, {-321, 1}, {-211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2023_I2099998);

} ```