Rivet analyses

title: BELLE_2006_I658082

Mass distributions in $B^-\to\Lambda_c^+\bar{p}\pi^-$

Experiment: BELLE (KEKB)

Inspire ID: 658082

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 97 (2006) 242001

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of mass distributions in $B^-\to\Lambda_c^+\bar{p}\pi^-$. The mass distributions were read from figure 2, which is not corrected, while the corrected helicity distribution was read from figure 3.

Source code:BELLE_2006_I658082.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B- -> Lambdac+ pbar pi- class BELLE_2006_I658082 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2006_I658082);


/// @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);
  // treat Lambda_c, Sigma_c and sigma_c* as stable
  BP.addStable(4122);
  BP.addStable(-4122);
  declare(BP, "BP");
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
  }
  book(_h[2], 2, 1, 1);
}


/// 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 = 1;
    if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 3, mode))
      sign = 1;
    else if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 3, modeCC))
      sign = -1;
    else
      continue;
    const Particle& lamC = BP.decayProducts()[ix].at(sign * 4122)[0];
    const Particle& pbar = BP.decayProducts()[ix].at(-sign * 2212)[0];
    const Particle& pim = BP.decayProducts()[ix].at(-sign * 211)[0];
    double mLamCPi = (lamC.mom() + pim.mom()).mass();
    double mPbarPi = (pbar.mom() + pim.mom()).mass();
    double mLamCPB = (lamC.mom() + pbar.mom()).mass();
    if (mLamCPi > 2.6 && mLamCPB > 3.5) _h[0]->fill(mPbarPi);
    if (mLamCPi > 2.6 && mPbarPi > 1.6) _h[1]->fill(mLamCPB);
    if (mLamCPB < 3.6) {
      LorentzTransform boostB = LorentzTransform::mkFrameTransformFromBeta(
          BP.decaying()[ix].mom().betaVec());
      FourMomentum pLamC = boostB.transform(lamC.mom());
      FourMomentum pLamCPB = boostB.transform(lamC.mom() + pbar.mom());
      LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pLamCPB.betaVec());
      pLamC = boost2.transform(pLamC);
      double cTheta = pLamC.p3().unit().dot(pLamCPB.p3().unit());
      _h[2]->fill(cTheta);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h, 1.0, false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
const map<PdgId, unsigned int> mode = {{4122, 1}, {-2212, 1}, {-211, 1}};
const map<PdgId, unsigned int> modeCC = {{-4122, 1}, {2212, 1}, {211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2006_I658082);

} ```